This article is a brief report on the course of development, and the present condition, of the non-ferrous metal industry in India observed by the writer during his late trip there (October 1951-January 1952).
It deals chiefly with (1) the current condition of the aluminum industry in India; (2) bauxite mines and deposits; (3) operational condition of refineries and rolling-mills; (4) programme of supply and demand, and statistics on export and import, of aluminum; (5) protective measures taken by the Indian Government, for the aluminum industry; and (6) programme for the future development of non-ferrous metal resources in that country, accompanied by a rough description of the condition of supply and demand of antimony and copper, how lead is variously used, and the prospect of demand for nickel, tin and zinc there, and the elements affecting the rise and fall of the prices of aluminum and other non-ferrous metals in the Indian market.

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Directly after the production of aluminum from imported bauxite re-opened in this country at 1948, the problem arised that the aluminum-ingot thus produced is somewhat brittle, compared with the imported one of same grade of purity. The present investigation has been carried out in order to solve this Al₄C₃ problem fundamentally.
Adding up to 1% of Na, Al₂O₃, Al₄C₃. AlN to the aluminum havingt he purity of 99.9%, 99.5%, 99.0%, respectively, the effect of these impurities on the mechanical properties of the aluminums was studied. Results obtained may be summarized as follows.
Generally, with the addition of natrium, the hardness of aluminum increases, and the elongation, especially the elongation at high temperature (400°) decreases, while the tensile strength remains almost unaltered.
The shock value decreases with the addition of natrium, showing, in brief, the increase in britlleness.
The above-mentioned tendencies become conspicious, as to the purity of aluminum decreases.
The addition of alumina (Bayer-alumina) shows very small influence on the mechanical properties of aluminum, while it makes the grain finer. With the addition of aluminum carbide, the elongation at high temperature (400°) decrease, while the mechanical properties at room temperature are almost unaltered. The increase of nitrogen makes aluminum some what britlle, showing the increase in tensil strength and the decrease in elongation.

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The thermal conductivity of layers of air separated by sheets of parallel aluminum foils at equal distances is discussed theoretically and confirmed by some experiments.

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The authors dealt with the corrosion behavior of aluminum alloys in contact with mild steel or brass and methods of its protection. In the first place, regarding various kinds of aluminum alloys-2S, 3S, A51S, 52S, 56S and ND-and other metals, the relative potentials to platinum pole in the aqueous solution containing 5.85%NaCl and 0.3%H₂O₂ were measured. Also in regard with 2S treated by means of various kinds of surface-preparation processes-anodizing, MBV, BV, phosphoric acid-alcohol and etc. -the similar measurement was carried out. Further on, the protecting effects by inserting zinc chromate paste, zinc sheet and cadmium sheet between aluminum alloy plate and steel or brass plate were measured based on the drop of tensile strength and elongation after immersion for a month in the previous solution. Insertion of zinc sheet proved best result and other two were next to it. But any of them was better than direct contact.

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The diagram and the electric conductivity of magnesium electro-bath have a great effect on magnesium electrolysis. They were measured, especially for MgCl₂-CaCl₂-NaCl.
In the electric conductivity measurement, Wheats stone bridge was used. The amplifier and the cell was designed to be accurate. The diagram was made by the thermal-analysis.
The results are sa fallows:
1) The electric conductivity decreases linearly as temperature.
2) The electric conductivity decreases suddenly near the melting-point.
3) Calcium chloride have a large effect on the electric conductivity of bath.
4) The knick pointn ear the melting point in the electric conductivity-temperature curve has the same temperature as in the thermal analysis.
5) A ternary eutectic is formed at 432°C. MgCl₂ 33%, CaCl₂ 21%, NaCl 46%.

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This paper refers to how to determine the most economical blank shape of aluminum strips for deep drawing of rectangular bexes. Some date for computing the limits for cupping rectangular shells are given herein.
The results of my study can be summarized as follows:
1) It is of most importance to take into cosideration the effects of corner radius (C), width (W) and side length (L) of the finished articles, even after bottom corner radius (D) and bottom side radius (B) were chosen most suitably.
2) In case the limit is expressed in the term of the ratio of blank corner radius/box corner radius=OG/C, this ratio increaes almost directory proportionally to the ratio of box side length/box corner radius=L/G up a maximum of 4.0-5.0.
3) It is desirable to take blank corner radius (OG) 5-10% longer than the calculated length.

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There are many reports on researches concerning the equilibrium of sodium aluminate solutions, but few reports have been published from the thermodynamic point of view. because theyare metastable and easilt over saturated with respect to Al(OH, )3. In order to contribute to this part of research, the following experiments and calculations of the equation were carried out.
One of the writers (Kitajima) obtained the values of vapour pressures of caustic soda solutions and sodium aluminate solutions (containing a small amount of impurities) by the pressure reduction method with variations of temperature 40, 60, 80, 100°C (t); Na₂O concentration 100, 200, 300g/l (n); and Al₂O₃/Na₂O mol ratio 0-0.6(m).
From these observed results, the other writer (Mitsugi) obtained the following experimental equation with the above variables t, n, and m. The experimental values of the vapour pressure of caustic soda solutions, however, were corrected according to those based on the Int. Crit. Table and the relation was studied from the temperature variation of the activity of water.
P=Pw-4.02•10^-3e^0.04317t.n^{1.149+3.72t.10-3-2•9t2.10-5-3.24}me^0.0223t-6mnt^4.8×10-11
Pw shows the vapour pressure of pure water at t°C. As to the accuracy of the equation, calculated values for caustic soda solutions of various temperatures and concentrationes were compared with those based on the Int crit. Table, and the accuracy was found to be ±2mm Hg, and in case of sodium aluminate solutions, the standard deviation. between the observed values was calculated for solutions of various temperatures, the result being as follows;

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A few researcher announced that the change of electric resistance in molton aluminum. The change at 765° is effected by Fe and Si content and is probably due to the behaviour of these impurities. The temperature in the visinity of 750°is considered as a suitable refining temperature for molton aluminum and its alloys. The authors studied the effect of some fluxes and Cl₂ gas on removing of slag and gas. The fluxes which are almost used in foundry, are considerably weaked compared with Cl₂ gas. After it is passed, molton aluminum improved its casting properties according to setlling time. The change of properties according to settling time is calculated as follows: Let v is the ascending velocity of gases, then we have v = 2r²d₀g/9η. Where r: radius of bubbles, d₀: density of medium, g: gravity η: coefficient of velocity. Let 1 is the layer of molton aluminum and t is the scattering time of gases, the scattering time is given by t = 1.7 × 10^-3•l•η/r². If η = 0.01 (at 750°).
r = 10^-3cm and l = 140cm are substituted, then we have 11min. which coincide with the value obtained from our experiment.

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Aluminum and its alloys absorb various kinds of gas while they are in a molten state, and, when they are cast, these gases absorbed therein in excess of the normal limit while they are molten will released in the course of their solidification and cause pinholes or blowholes in their castings, and cause blister in case of sheet after annealing, thereby adversely affecting the quality of the products and increasing the risk of their rejection to the great annoyance of the makers concerned. As a consequence, numerous and varied researches hav been made in the cause of such defects and for the prevention thereof and the findings have been applied to actual factory operations with fairly commendable and efficient rusults. To-day, however, when the melting of these light metals is carried on a far larger scale than formerly, many cases, where the methods of prevention of said defects hitherto followed have failed to give satisfactory results, are reported.
Confronted with such a situation, the writer has keenly felt the necessity of seriously reconsidering the adequacy or otherwise of the methods of melting aluminum and of degasification there of employed heretofore. The methods of degasification of aluminum and its alloys so far studied and put in practice aim, one and al, at removing the gas contained in them while they are molten. At the process when aluminum turn from a liquid into a solid, namely at coexistense of solid and liquid it will release the gas contained therein in excess of the normal limit, but this peculiar characteristic has never been utilized. Propory speaking, the methods of melting aluminum so far in practice represent a disregard for the aforementioned characteristic of aluminum and merely unstudied application of the metheods of melting other kinds of metals to aluminum.
The writer holds the view that the release of the surplus gas in aluminum, which has generally been considered to take place at the process of the metal turning from a liquid into a solid, must occur at the process when it turns from a solid into a liquid also, viz. liquid (L)_??_s + L_??_golid (s). On the basis of this view, I have conceived an idea of liberating the released gas into the air speedily without causing it to remain in molten aluminum. In other words, the release of the surplus gas is to be so made naturaly as to take place coincidentally with only the melting process of aluminum. For an example in the case of melting a large quantity of aluminum ingot in a reverberatory furnace, for instance, the upper art of ingot is melted first and sinks down to the unmolten part beneath, mingling with and gradually melting it, but the gas released at this time will remain in the melt without being exhausted. Therefore, it is prime importance to make this gas which release in the cause of melting freely evaporate into the air. If this is possible, the degasification of molten aluminum can be achieved thereby. To put it in an extrem explanning, it is advisable to adopt a method that, in melting any aluminum ingot each molten molecule can be separated from solid as soon as it becomes melted-It can be carried out with a melting-furnace, provided with a melting support near the grate and slightly higher than the furnace-bed with an inclination to the holding-tray, and so made as, when an aluminum ingot to be melted is placed there and melted, the molten aluminum will move, bit by bit, on to the bottom of the tray without being over-heated. This method is already being actually used with excellent results. in practical production. Writer named it "candle-like melting"
The above stated research was made principally with reference to the degasification of surplus gas in molten aluminum.

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Hitherto the measurment of gas in aluminum ingot has been carried out by analyzing it extracted by vacum meltirg of the ingot, but the result of this measurment is difficult of application directed to actual factory operations in as much as the value measured is subject to a fairly marked change according to the device used for the measurment, preparation of test-pieces, conditions under which the gas is extracted, etc., coupled with complicity in the method of its extraction. Such being the case. the writers have studied the method of collecting and measuring the gas emanating direct from an aluminum ingot by boring holes in it, while it is immersed in a light oil, and that of collecting and measuring the gas emanating from the ingot by melting it in a caustic soda solution, and as certained that these two methods are identically effective in feeing and measuring the gas inquestion with such results as are generally applicable to actual factory operations, as the below-mentioned experiments indicate.
1. Gas in Aluminum ingots:
The gas contained in aluminum ingots differs in volume to some extent according as the ingots are made by different makers and according to the time of their manufacture even in those made by the same maker.
2 Relation between casting temperature and cooling rate and volume of gas:
Experiments made of the aluminum ingot cast at 660°, 700° and 750°C. show that the higher the temperature, the larger the volume of thegas contained in it is. It has also been ascertained that, in case the aluminum ingot once heated at a high temperatre s cooled down to its former normal temperature, the volume of gas absorped by the ingot its found notably larger than it was before being subjected to high heat. Further, it has come to the writers, knowledge that, in case the same metallic mould is used in casting aluminum ingots, the gas contained in them will decrease in volume follow the rise of the temperature of the mould, reaching the minimum at 150°C, but htiw again increasing as said temperature approaches 300°C.
3. Degassing effect of chlorination:
In case molten aluminum of about 10kgs, is left untouched after chloride, is passed through it for 10-20 minutes, the gas contained in it will be found to be small in volume within minutes subsequent to the passing of. chloride, but in case the molten mass is left as it is, it will again increasingly absorb the gas. Comparision of the gas measured and the specific gravity of it testifies to this tendency.
4. Difference in volume of gas in aluminum ingot by the several melting and effect of degassing with zinc chloride:
If the ordinary meiting method and the remelting method hitherto in practice a special method of melting, where by the ingot is degasified at the time of melting, are employed, it will be found that the volume of the gas in the molten aluminum will decrease mere, the more ease is taken in degasifying the melt and that, if the method usually in practice which merely aimes at melting it is used, the melt will absorb more gas than that already contained therein It has also been ascertained that degassing by means of chloride is effective when the gas contained in the melt is large in volume, but is not so when the gas in question is limited in volume and remain below a certain percentage.
5. Melting method usually in practice and special melting method with reference to factory operations and gas contained in melt:
In case an aluminum ingot is melted in a 10-ton reverberatory furnace, the volume of the gas contained in the melt while it breaks down, is subjected to degassing treatment, and comes out to the holding tray of furnace and is being cast can be measured, and the behaviour of the gasclarified, in relation to the time required for these operations.

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In our former report, the relationship between thetextures, anisotropy and earing behavior of commercial pure aluminum sheets cold rolled about 55% was studied, and some consideration was given on the mechanism of earing behavior.
Now, on the extended reduction range from about 37% to 95%, how the anisotropy changes of commercial pure aluminum sheets are occured by the final annealing are systematically studied. The results thus obtained are:
1) The softening velocity evaluated from hardness-annealing time curve at constant annealing temperature increases with the increased reduction to 84% cold reduction, and over this, the softening velocity decreases with the increased reduction.
2) The anisotropy changes of aluminum sheets by the short time annealing in salt bath at 300°C, 400°C, and 500°C are studied, and it was recongnized that the heighest ears with 0° and 90° direction from rolling direction were formed at the point of about 84% reduction.
Therefore, it is assumed to exist the favourable conditions with lower ear formotion in the both side of this point.
As the anisotropy changes are more sensitive to the change of the degree of reduction at the side of higher reduction than lower one, it is suitable to adopt the lower reduction side so for as the grain growth by the following annealing is not suffered.
However, the exact control of reduction could be taken, it is more suitable to adopt the higher reduction side because of no suffering from grain growth, and in this case, the allowable reduction range are extended with the increase of annealing temperature.
3) In the case of long time annealing in air bath the degree of anisotropy of recrystalliged Al-sheets are most weak at the middle reduction of about 60%.
4) The anisotropy of Al-sheets after recrystallization are increased with increased annealing temperature and with the prolonged annealing time generally.
5) The annealing texture of the severly rolled sheets (92.5 and 95.2% cold rolled) whdih gives 45° ear to R. D. was examined by the microscope and it has proved that it consists of the similar texture to the rolled one and the cubic texture mainly.
The former texture is predominant and the latter inferior.
From this textures, we can expect the 45° ear formation as the former texture has the characteristic of 45°ear formation and the latter 0° and. 90°.

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Recently the alloy 14S has again attracted much attention as structural material. For it contains much Si and Fe which generally tend to be increased when light alloys scraps are repeatedly melted. And it hasa high tensile strength and yield point such as 49kg/mm² and 4.2kg/mm² respectively.
In order to understand this alloy more in detail, we prepared many alloys the composition of which are in the range of Cu 4.0-4.5%, Mg 0.0-1.5%, Mn 0.6-1.0%, Si 0.2-1.6%, Fe 0.2-0.7%, and which were quenched, natural-aged and tempered. Their mechanical properties were compared. The results are follows.
1) There is only a slight difference between the effect of 4.0%Cu and 4.5%Cu, and 0.6%Mn and 1.0%Mn. The proper range pf Mg has proved to be 0.5-1.0%.
2) In the case of 0.2%Si, the tempering effect is small, but when 1.0%Si is contained, its effect is so large, that is, the increase in yield point is as large as more than 10kg/mm² and the decrease in elongation in nearly while the tensile strength is not largely effected.
3) The bad effect of Fe decreasesin proportion to the increase of Si content. When Si content approaches 0.8%, the effect of Fe practically disappeares.
4) The experiment was also conducted on the temper-hardening characteristic of these alloys, varying the time and temperature for heating. The results show that (a) the higher the quenching temperature, the higher is the maximum hardness, (b) the lower the Si content, the longer is the time to reach maximum hardness, (c) the most adequate tempering temperature for 14S is 170°C, while heating at 150°C requires a rather long time, and at 200°C the maximum hardness becomes lower. As for 24S, 200°C is more suitable.

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In our previous work, it was found that the recrystallization temperature of 99.9%Al depends upon the initial grain size of annealed sheet. On the standpoints of practice, the authors have investigated the influence of hot rolling condition on the recrystallization temperature of 99.9%Al in this paper.
Then, it was found that the hot rolling temperature affects a little, but the hot rolling reduction has not any effect on the recrystallization temperature, and also a remarkable difference between the hot and cold rolling and the cold rolling could not found. It is concluded that the hot rolling condition has not a remarkable effect on the recrystallization temperature, which also depends mainly upon the initial grain size of annealed sheet. That is, the recrystallization temperature of high purity aluminium (99.93-99.94%) is not directly effected by the hot rolling condition and it changes between 320°C and 280°C corresponding to its initial grain size which is varied from 300 to 90 grains/mm² in practice by the rolling and annealing conditions.

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General properties of Hydronalium containing 5% and 10% of Mg are discussed according to Table 1 and Table 2.
On advantage of flux, authors explained from their experiments. Flux used on their experiments is that used for melting of Mg shown in Table 4.
The killing time about one hour is necessary to separate flux from the melt, by means of this process desirable mechanical properties and resistance for corrosion will be acquired.
The solution treatment of hydronalium contained 10% of Mg will take a long time about 24 hours or more even at 450°C, then it will become tensil strength 35.6kg/mm², and elongation 20%.
Effects of a small amount of Zn, Cd, Sn and Si in hydronalium are studied by tensile and corrosion tests. On the case of hydronalium contained 10% of Mg, presence of even 0.5% of each element will depress its tensile strength and elongation (Fig. 1), but on the case containing 5% of Mg the depression is small rate comparatively (Fig. 2).
It seems that the presence of Zn makes hydronalium to corrosible.

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This paper describes the tolerances for die castings and gravity castings.
The authors measured tolerances of both castings.
Then by this measurment we could know the properties of tolerance for the castings.
We could consider that the tolerance of castings can be divided in next three elements.
Namely (1) Mechanical tolerance
(2) Tolerance of the dies
(3) Metallurgical tolerance
The tolerances of (1) & (2) can be minimizcd by care of the machining of dies and the operations of casting.
If we put the metallurgical tolerallces as ΔL.
ΔL=l₂₀[αf(tf₁-tf₂)-α(ts₁-ts₂)]
l₂₀: dimenoion of the dies.
αf, tf: expansion coefficient and temperature of the dies.
ts: temperature of the castings begin to shrink.
α: expansion cocfficent of the castings.
By above formula ΔL can be destermined by the temperature of die and castings because ts related to casting temperature.
Then the ΔL, which is the important parts of tolerance for castings, can be minimized by the fixed temperattlre of dies and casting temperature. The authors could acertain the metallurgical tolerance is 10^-3-10^-4 at Aluminum alloy die castings and 10^-3 at aluminum alloy gravity castings by this experiment.

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Some metal-arc electrode coated with flux was produced and the welding test on aluminum and its alloys (2S, 52S, 56S, and 61S) was carried out.
The results obtained are summariesed as followe:
1) By employing these electrodes, the welding work is easy, namely the arc stability is good and the bead is uniform.
2) Tensile and bending properties of the welding joints are approximately equal to that of gas-welded joints.
3) Blow hole and slang inclusion in the bead is rare.
4) Welding work in horizontal and vertical position is performed without difficulty.
5) Workability and properties of jointed parts welded by special corrosion resistant alloy metal-arc electrode (C. R. A.) prodeuced in our laboratory is excellent.

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Hitherto lead has been used mainly as cable sheath material.
However, new superior materials are demanded to get rid of the weak points of lead sheath as well as on acount of the shortage of lead, accordingly, study of aluminum has been conducted to meet this demand.
There are several kinds of methods in aluminum sheathing, but, the writer manufactured it by sinking method. It's special feature is, as compared with lead sheathed cable, that it ts light, hard and has durabity against vibration and creep.
However, on the other hand, it has inferior points in flexibility and corrosion etc, but as the result of various experiment, we have proved that they are harmless in practical use, and it has been answering the purpose of utility.

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It has long since been in practice to protect telephone and power cables with a lead or lead alloy sheath. on the other hand, studies have been made on substitutes for such sheath. Quite lately, we have succeeded in the manufacture of aluminum-sheathed telephone and power cables. According to the process developed by us, cable cores are first drawn into a long aluminum pipe and then the pipe is compressed by a die so that it may closely tighten the cores, Therefore, the aluminum sheath is seamless and free from pinholes or any other defects and regarded as an ideal tubular sheath.
The results of various tests made by us show that the aluminum sheath is superior to lead sheath in respect of resistance against vibration fatigue, mechanical strength and strength against creep. Moreever, it is much lighter than, and can compare favourably with, lead sheath in point of anti-corrosiveness in case it is used for aerial cables. Aluminum sheathed cables can also be installed or jointed more easily and securely than lead sheathed cables.
The results of the actual installation and jointing of thousands of meters of our aluminum sheathed cables by way of trial testify to the aforesaid merits. It is safe to say that they represent a novel type of cables rather than mere substitutes for lead sheathed cables.

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This essay is on the proposed dimensions of various aluminum building materials discussed on the committee of architecture in the Light Metals Society of Japan, consisting on the standard size and weight of plate, strip, bar, wire, foil, pipe, structural angle, I beam, channel, band, rivet, wood screw, bolt, washer, nut, nail, etc.

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Aluminum windows are gradually becoming popular in this country. However, majority of our architects and building engineers have little knowledge about aluminum alloys. Some complain about aluminum because it is too soft while some complain about its corrosiveness. The former used 2S where the material shoud have been harder while the latter used duralumin series when the anti-corrosive nature was important. They all disliked aluminum ever since.
Therefore, all dealers and makers must be extremely careful about the window materials especially at the present stage when the aluminum windows are becoming popular so that the builders are supplied with correct materials at the reasonable price and eliminate all possible complaints due to the misuse of the material. The important features for the window material may be summarized in four following items:
1. Non-corrosiveness
2. Hardness
3. High yield stress
4. Productivity
(1) and (4) are self-explanatory. Hardness is important because such material cannot be scarred easily. Lastly, high yield stress is important in two folds. It prevents the window parts from casual deformations. It also saves the material consumption, hence cuts down the window cost.
Up to the present. there are few aluminum windows reported to have been installed. Materials were 2S, 3S, or SA3, all extruded. All of these materials are non-heat-treatable. Hardness and yield stress of extruded sections of these materials are very small as conpared with those of 63S-T5, the heat-treatable aluminum alloy. At present, 63S-T5 or 63S-T6, seems to be the only alloy which satisfies all of the above mentioned requirements for sash sections. The writer's study on catalogues of the United States, for instance, Sweet's File, also indicates this. More than 60% of aluminum window suppliers adopt 63S-T5.

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After the war, the aluminum alloys found its uses in the industry in time of peace. But designers and users only had so poor knowledge for these materials that many troubles have been caused in the field where aluminum alloys barely found its uses.
Then, taking the utmost care for the specialities of these materials, we successfully designed the ladder and the reeling machine as described in this report.
Main factors in designing these assemblies are shown as follows.
(A) The ladder.
(1) Safety; This ladder must be so strong that it is safely used on the high trass of the electric power transmission tower.
(2) Lightness; It must be easily carried folding double and hanged up to the high trass.
(B) The reelirg machine.
(1) strength; It must be stronger than the wooden one as same weight.
(2) Vibration; It is little in using condition for their constructive rigidity.
(3) Adjustment; User can adjust its circumference.

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We studyed what effects were given on the experimental results of corrosion or abrasion resistance measured according to the inspecting standard JIS H 8601, by the variation of pressure in steam sealing process, and obtained following results.
(1) The corrosion resistance of anodic oxide film increases at the ratio of 2.1sec./lb./in². in proportion to the increment of steam pressure (sealing time is constant at 20min.), while its abrasion resistance decreases a little.
(2) The corrosion resistance of anodic oxide film increases in accordance with the increment of sealing time from O to 90min. (the steam pressure is constant at 75lb./in².), but its abrasion resistance decreases slightly.

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The Effects of bath-condition include those of concentration, temperature and superannuation of electrolyte.
If voltage and temperature of bath are constant, the higher the concentration of sulphuric acid is, the poorer the lustre is, but the other hand, the stronger the adsorptive power is. (See Fig. 7)
If voltage and concentration of bath are constant, the higher the temperature is thepoorer the lustre is, but the other hand, the stronger the adsorptive power is. (See Fig. 8)
When the electrolyte grows old and. in other words, the content of aluminum sulphate in bath increases, the lustre of coatings is rather better and the adsorptive power is not changed. (See Fig. 9)
Finally, as for the inhibitter to corrosion by sulphuric acid glycerin is added in bath. In the condition of this experiment the addition of gram glycerin per litre of electrolyte gives the best results for lustre of film and not changes the adsorptive power of it. (See Fig. 10)
Surface of this film is as smooth as that of enamel ware.

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We explained the several kinds of Sodas washing methods. employed for the purpose of degreasing on the surface of Aluminum, and its mechanism. Then, picking up the electrolytic washing method, we carried out the systematic experiments to make clear the correlations of current density, concertration of soda and temperature. Furthermore, we experimentally illustrated about the degreasing mechanism in the case of applying mineral oils which cause no soaponification.

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What I wish to recommend as the excellent coating process of aluminum alloys are as following:
1) For the small-size and large-size products, the three-step coating process of the special primer, zinc chromate-phthalic resin enamel and phthalic resin enamel (or aluminum paint) is the best.
2) For the small-size product, the good process is to paint the zinc chromate-phthalic resin enamel, next the phthalic resin enamel on aluminum alloys which were electro-oxidized or treated with the phosphoric acid-alcohol solution.
Several experiments brought me to the adoption of these above coating process.

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In making the quatitative spectrographical analysis of the impurities in aluminum and aluminum-oxide mentioned in this report, the writer used throughout a crystal spectrometer of the Qu-24 type made by The Zeiss of Germany and its accessories.
A quantitative spectrographical analysis of aluminum is possible with a Feuessner spark generator (the connection diagram of which is described in the principal thesis) under the graphical conditions, viz., voltage: 12, 000v.; condencer capacity: 0.0066μF.; inductance: 0.8mH; spark gap: 2mm.; and the diameter of specimen: 3.8mm.
It is usually the case that, in carring out the quantitative spectrographical analysis under consideration, several standard specimens are photographed on one and the same dry-Plate with an unknown specimen. However, in view of the fact that the blackening between the spectrums of aluminum is uniform on the same plate on the same graphical conditions, this analysis can be done without the use of any standard specimien, when and if one of said spectrums is specifically taken as corresponding to a certain percentage of impurity. This method will be specially dealt with in a concrete manner.
In making a quantitative analysis of silica, ferrous oxide and sodium oxide contained in aluminum oxide, holes are made at both opposite ends of pare carbon electrodes, each having a diameter of about 5mm., and they are filled with alminum oxide suitably ground in an agate mortar and subjected to a spark generated with a Feuessner spark generator under the conditions, viz., voltage: 12, 000v.; condenser capacity: 0.006μF.; inductance: 0.08mH.; and the distance between the electrodes: 2mm. The percentage of the impure contents can be ascertained by spectrc-analyzing the light emanating from the po der, with which the holes are filled.

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