246 ANNUAL OF SCIENTIFIC DISCOVERY. 



action of the former is that of the oxidation of the tissues, while the latter 

 owes its power as a caustic to its power of extracting the elements of water 

 from organized bodies, behaving like the exsiccated salts previously men- 

 tioned, with which it is sometimes judiciously combined to prevent the 

 spreading of the acid beyond the parts to be destroyed by reason of its 

 fluidity when uncombincd. 



Chloride of gold has been extensively employed, generally in combination 

 with other caustics, in some of the continental hospitals. When placed in 

 contact with organic matter, this salt is reduced to a metallic state similar 

 to the action of nitrate of silver; but, as far as my experience goes, it is 

 inferior as a caustic to the silver salt, because of the large quantity of oxid- 

 izing material which is set free when the organic matter is treated with 

 nitrate of silver. Among the conservative caustics, arsenic and its com- 

 pounds will find its proper class; for although arsenic is poisonous to living 

 tissue, it is a powerful antiseptic agent. It forms no combinations with 

 dead or living tissue, and only a feeble one with albuminous matter : and 

 from this cause it must be regarded, in a chemical point of view, as a very 

 inefficient caustic. 



Chlorides of antimony and iron, which have been used as caustics, ex- 

 hibit a mode of action similar to chloride of zinc. The very feeble action of 

 the latter must, in some cases, be its principal recommendation. 



It will be evident from the previous statements that chemistry will supply 

 us with an indefinite number of caustics; for it is clear that whatever 

 decomposes or combines with living tissue sufficiently to kill it, is, to all 

 intents and purposes, a caustic. It is equally manifest that, while it is the 

 essential condition of every substance professing to be a caustic, that it 

 should kill the living tissue, it by no means follows that all caustics per- 

 forming this condition should destroy or dissolve away, as it were, the tissue 

 when no longer possessing life, for this latter property belongs to a distinct 

 class of caustics. 



I am aware that I have not noticed the so-called irritant action of caustics ; 

 but, in explanation, I reply, that the consideration of this action is foreign 

 to the purpose of this communication, and, moreover, a subject not within 

 the province of the chemist. Me d. Times and Gazette. 



THE CHEMISTRY OF GUNPOWDER. 



Although the processes involved in the combustion of gunpowder, and 

 determining its mechanical action, would appear to be very simple, accord- 

 ing to what is at present known of this subject, still our acquaintance with 

 the precise nature of these processes is exceedingly slender and imperfect. 

 The consideration of the subject, since its first, and still most important ex- 

 perimental investigation, undertaken by Gay-Lussac more than thirty years 

 ago, has led to such discordant results, tho*, at the present time, there is no 

 chemical view of it that is at all consistent with experience. The normal 

 composition of gunpowder may be represented in chemical proportions, by 



Cs + S + KO, NO.5, 



Or one equivalent of nitrate of potash, one equivalent of sulphur, and three 

 equivalents of carbon (charcoal). Supposing the whole of the carbon to be 

 converted into carbonic acid, and the nitrogen to be liberated, Cs + S + K 



