Chemistry Pamphlets Volume 3 (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1897 Excerpt: ...prepared with nitric acid alone, but practically, this is never employed, since by the addition of sulphuric acid a great saving of nitric acid and of time is effected. There is not very much known about the best proportions of acids for preparing collodion cotton; the published statements vary from 1 sulphuric to 1 nitric acid up to 6: 1, and are partly decidedly misleading (compare above sub C). We have in Section III, C, shown the results obtained with that proportion of acids which is probably the best for collodion cotton; viz., about 1: i, with from 18 to 20 per cent, water in the mixture. I now give the results of experiments (with Bebie), intended to study more completely the conditions of making collodion cotton when varying the quantities of the acids and the proportions of water. No. I 2 3 4 5 6 7 8 9 10 11 12 '3 14 No. 1, prepared with too little water, is still a guncotton. No. 2 is evidently identical with Mendelejeff's " pyrocollodion," both as to its nitrogen percentage and its solubility. The remaining samples are collodion cotton of various nitrogen percentages and various yields. The differences between this series and the experiments described Diagram 2. in Section III, C, where the proportion of acids was i: i, is made very clear by the diagram appended here, in which the former series (with acids--i: i) is represented by the dotted line; the full curve i shows the results obtained with sulphuric to nitric acid = 3:1; total acids = 30 to 1 cellulose; curve 2 refers to the same proportion, but 12 acids to 1 cellulose; curve 3 refers to the acid proportion of 5 sulphuric to 1 nitric acid, and a total of 30 acids to 1 cellulose; curve 4 refers to the same proportion of acids, but 8 total acids to 1 cellulose. We see that the prop...