22 MODERN SCIENCE READER 



Schonbein announced in 1845 his ability to make an explo- 

 sive which he termed guncotton, and a year later Bottger 

 made a similar announcement, and on a conference being 

 held between these chemists their methods were found to 

 be identical. The method was not disclosed at the time, 

 since it was hoped that the German government would 

 purchase the secret, but in a very short time several investi- 

 gators solved the problem, and attempts to make the new 

 explosive commercially were common. Unfortunately the 

 earlier product was unstable, and several disastrous acci- 

 dents occurred which led to the abandonment of the experi- 

 ments, except in Austria. General von Lenk, who continued 

 experimenting in that country, showed that if sufficient 

 care was taken to ensure complete nitration and to remove 

 all traces of free acid from the finished material, the sub- 

 stance was stable. He introduced a method of manufacture 

 which was improved by Sir Frederick Abel in 1865. The 

 physical character of the cotton fiber is such that it presents 

 every obstacle to the removal of free acid, since it is built 

 up of capillaries, but by reducing these tubes to the short- 

 est possible length, as in Abel's process, the removal of acid 

 is facilitated. 



Since water is a product of the reaction of nitric acid on 

 cellulose, the nitric acid would become diluted, forming 

 "collodion cotton " instead of the more highly nitrated 

 guncotton, and, therefore, sulphuric acid is used with the 

 nitric acid to absorb this water, the usual proportions being 

 3 parts by weight of sulphuric acid (1-84) to 1 part by 

 weight of nitric acid (1-52). Cotton waste, which has been 

 picked, cleaned, cut into short lengths, and dried, is dipped 

 in 114-pound charges in the acid, removed after five or six 

 minutes, the excess of acid squeezed out, and the cotton 

 placed in cooled earthenware pots for some twenty-four 

 hours for nitration to be completed. The guncotton now 

 goes through the lengthy process for removal of all traces 

 of acid, starting with the removal of the greater portion of 

 the acid by a centrifugal extractor, washing in water till 



