1866.] 



Presidenfs Address. 



277 



Captain Foster's experiments in his eauatorial and antarctic voyage (1828- 

 1830) was jJ,^. 



In our Transactions of the present year we have an elaborate and valuable 

 memoir by Mr. Abel "On the Manufacture and Composition of Gun-cotton," 

 pointing out the causes of the difference in the analytical results obtained 

 by many of the earlier inquirers into its nature, and confirming its compo- 

 sition as determined by Crum and more fully proved by Hado w, and again 

 stated by the Committee of Chemists who reported on Baron von Lenk's 

 Gun-cotton. In pursuing these analytical inquiries, Mr. Abel has tested 

 the methods, both synthetical and analytical, formerly employed, and has 

 devised some modes of analysis of his own. The multiplied and varied 

 experiments which he has made leave no room to doubt the accuracy of 

 his results, though they differ from those of M. Pelouze. 



"With regard to the processes of m.anufacture, Mr. Abel has proved by 

 experiments, both in the laboratory and on a m.anufacturing scale, that 

 Baron von Lenk's method, although it does not at first sight present any 

 important features of novelty, yet unquestionably ensures the attainment of 

 greater uniformity and purity of the product, though Mr. Abel has him- 

 self suggested one or two modifications of importance. The most valuable 

 practical result deduced by Mr. Abel from his experiments is, that the 

 instability which has been observed in certain samples of gun-cotton, pro- 

 ducing the gradual decomposition of such samples by prolonged keeping, is 

 due to insufficient purification of the material employed, in consequence of 

 which oxidized products of small quantities of resinous and other foreign 

 substances are formed in the manufacture, and are still retained by the tu- 

 bular fibre of the cotton. These undergo decomposition, and the change 

 extends to the mass. Many of these impurities are removed by the action 

 of the alkaline bath upon the cotton before treating it with the nitric and sul- 

 phuric acids, and others may in great measure be dissolved by a final boil- 

 ing with a weak alkaline solution. 



Mr. Abel's paper is an important contribution towards a more complete 

 knowledge than has hitherto obtained of the precautions which are required 

 in the manufacture of gun-cotton in order to diminish still further both 

 the risk of accidents, and the liability to injury of the material when not 

 stored, — as it ought invariably to be when no paramount reason requires an 

 exception, — either under water or in a state of moisture precluding ignition. 



Since my Address last year little has been done in regard to the success- 

 ful application of gun-cotton to the large ordnance employed in the public 

 service. The desideratum for this purpose may be stated to be a form of 

 cartridge, which with the required velocity of the projectile on quitting the 

 piece, shall have produced an approach to an equality of strain upon every 

 point of the bore, from the instant of ignition to that of the discharge. 

 In tke absence of a test of the degree to which this is accomplished, ex- 

 periments on different forms of the cartridge are necessarily tentative, and 



