The results of nitrations at 25°C by 34 varieties of mixed acids, with which comparatively uniform nitrations may be expected, are shown in Appendix Table V. Comparing the relation between the nitrogen content and the composition of waste acids with the free energy of nitrating acid (Fn), that is calculated by assuming T as 25°C, the theory of the cellulose nitration is discussed as follows.
(1) Calculation of Fn. If the free energy of pure nitric acid is taken as standard zero, the free energy of the nitrating acid containing one mol of nitric acid (Fn) can be calculated by the equation-Fn=RT/x∫x0Pn/pdx-that is derived from Nernst's equation. Where x is the ratio of mol fractions of components; in the case of NO₃H.H₂O-System it is the ratio of mol fraction of nitric acid to that of water, and in the case of Nitric acid. Aqueous sulphuric acid solution-System it is the ratio of mol fraction of nitric acid to that of aqueous sulphuric acid solution.
(2) Theory of nitration. In the nitration of cellulose, the nitrogen content of nitrocellulose increases until it reaches a equilibrium with the nitrating acid. In other words, the nitrating capacity of the nitrating acid may be measured by its free energy. Although the effective nitric acid for nitration has been suggested by various forms, the esterifying capacity of nitrating acids can be estimated by the free energy of the nitrating acids containing one mol of nitric acid (Fn) in the scope of ordinary industrial mixed acid.
(3) Farmer's view of nitration mechanism. Farmer has proposed that the nitration of cellulose depends on the pseudo nitric acid in nitrating acid. But, since its concentration in mixed acids has not yet been determined, the free energy of the nitrating acid containing one mol of pseudo nitric acid (Fp. n) can not be calculated. In ordinary industrial mixed acid, however, its nitrating capacity can be estimated by Fn instead of Fp. n, for in these mixed acids the concentration of the uncombined pseudo nitric acid may be assumed constant if water content is not too small.
(4) Curves of iso-nitrogen content and iso-free energy. There is an intimate relation between the curve of equal nitrogen content and the curve of equal free energy in NO₃SH.SO₄H₂.H₂O-triangular coordinates diagram, and this fact explains that the nitrating capacity of acid mixture depends on its free energy (Fn). However, as the ratio of SO₄H₂ to H₂O by mol% approaches to 1, these curves break their parallerism. Perhps, this is due to various causes, but one of them is the cellulose-swelling action of the mixed acid used.
(5) Function of sulphuric acid in mixed acid. In addition to the dehydrating action, which means the maintaining the free energy of nitric acid at high level, sulphuric acid in mixed acids acts on cellulose as a swelling agent and affects on the uniformity of nitration degree, that has an influence upon the mean nitrogen content of nitrocellulses.

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By treating cellulose monobenzoate at 18-20°C. with mixed acid of following composition authors have obtained cellulose dinitrate mononitrobenzoate, C₆H₇O₂. CO₂C₆H₄NO₂.(NO₃)₂ by acid I and II, and mononitrate, C₆H₈O₃.CO₂C₆H₄NO₃.NO₃ by acid III.
The explosive properties of these nitrates are very similar to the nitrates of normal cellulose, but in comparison with the equally nitrated normal cellulose, these mixed esters i) are more stable, ii) are less hygroscopic, iii) burn at a slower rate, iv) are less soluble in ether-alcohol.

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The solubility in ether-alcohol of varying proportions of five varieties of different nitrogen contents in the temperature in terval -20° to +30° has been determined, and the nitrogen contents of the dissolved and undissolved parts estimated separately. The results are as follows :
Specimen A (N=13.23%) (Fig. 1 & 2, Japanese Original p. 255)
1) As the temperature falls, the solubility increases; the maximum solubility obtained with the composition ether 2 : alcohol 1 at -20° is twice as great as at an ordinary temperature.
2) A solvent of the composition ether 2 : alcohol 1 shows the maximum solubility at any temperatures.
3) Variation with temperature of the solubility is greatest in the solvent giving the maximum solubility, and correspondingly smaller in those of smaller solubilities.
4) As the temperature falls, the nitrogen content of the dissolved part increases, e.g. for a solvent of ether 2 : alcohol 1, the nitrogen content at 30° is 11.82% and 12.38% at -20°, and it diminishes with its solubility. Hence the nitrogen contents of the mass, which may be considered to have dissolved owing to the fall of temperature, have been calculated.
Fram the result above, it may be inferred that at 0°, the highly nitrated cellulose, gun-cotton, appears to begin to dissolve.
Specimen B (N=12.69%) (Fig. 3 & 4, Japanese Original p. 258)
This specimen, a pyrocollodion, dissolves better at a lower temperature and the solubility in solvents containing 14 to 50% alcohol varies from 60 to 100%, while the nitrogen content of the dissolved part remains the same.
Specimen C (N=12.24%) and D (N=11.50%) (Fig. 5 & 6, Japanese Original p. 260)
Both of these are highly soluble, and although the variation with the change of temperature of solubility is not distinct, the solubility appears to increase as the temperature falls; the former dissolves better in ether rich solvents, while the latter in alcohol rich solvents.
Specimen E (N=10.97%) (Fig. 7 & 8. Japanese Original p. 261)
Unlike the other four varieties, the solubility of this nitrocellulose increases with temperature and a mixture of equal volumes of ether and alcohol is a most favourable solvent.

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(1) クロストリジウム・アセトブチリクムに属する3株のアセトン・ブタノール菌(B. Y.菌,六所1号菌及びBacillus granulobacter pectinovorum)の古き(13～38年)砂培養の耐久性について試験した.
(2) 試験に供した砂培養中B. Y.及び六所1号の最も古いものは保存年数38年であるが,これらも試験した他の砂培養と同じく植菌後醗酵開始までにやや長時間を要したが72時間で種用として使用可能な程度に繁殖し5代員(G₅)の醗酵試験の結果,何れも極めて旺盛な醗酵を営み,とうもろこし及び切干甘藷の濃厚醪に於いて生成されたソルベント総量(アセトン,ブタノール,エタノールの合計)は2,100～2,290mg/100ccであった.
(3) 砂培養保存期間の短かかったものが長いものに比してソルベント生成量が必ずしも多かったとはいえなかった.
(4) 砂培養を植菌後5代目(G₅)の醗酵試験に於いてソルベントの生成量のやや少かったものも1代目(G₁)で作らせた胞子をheat shockした後種として再出発した5代目(G₅)の醗酵成績は前者に比して良化した.
(5) 長期間(29年間)醪のまま(砂培養とせず)保存した培養は全く醗酵しなかった.
(6) 上記の如く醪のまま保存したものを鏡検したところ,胞子数は相当多く見受けられたがいずれも相当甚しく腐蝕されているのを見た.これに反し上記の如く38年を経過した古い砂培養の胞子は,それを少量の水で抽出して鏡検したところ,その原形を全く保持し,新しい培養の胞子と全く同一の外観を呈していた.
(7) これを要するに,作製宜しきを得れば,クロストリジウム・アセトブチリクムに属するアセトンーブタノール菌の砂培養は,特に冷所に保存せずとも38年間の長期に亘って安全にその醗酵力を保存することが出来る.かかる菌が今後何年間更に醗酵力を維持し得るかは頗る興味あることである.
(9) たとい保存期間が短くても,砂培養を作った時の条件 (醪の種類,濃度,醗酵の良否,砂におろすまでの日数,乾燥の方法及びその程度等)が適当でないと,その砂培養の醗酵力の弱い場合のあることは筆者のこれまで経験したことである.

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