29-4 Injlammathn of comhujiibh Bodies •uiith 



that when the mixture acquired a certain degree of heat an explofion certainly took placr^ 

 except the retort Iv.i n pretty wide neck, and the neck was fimply introduced into a re- 

 ceiver with a confidcrable opening in it without any lute; or put into water, as in the lad 

 experiment : and even in this cafe I would not advife fo much of the fait to be ufed at one 

 time as is here mentioned. The fmall quantity of acid I was able to colleft in this way, 

 by adapting a loofe receiver, appeared to be a weak muriatic acid flightly oxygenated ; it 

 v/as of a dilute purple colour, which difappeared on its being expofed a (hort time to the 

 light : a fmall piece of iron dropped into it caufed it to become tranfparent immediately. 



It was a matter of much furprife to me, to find fo ftrong a fmell of nitrous gas produced 

 on dctompofing this fait with fulphuric acid. Now> as nitrous gas confids of azot and 

 o;(ygen, fuppofinjf tliis to be nitrous gas (for I do not aflert it to be fo, though I fhould 

 think the im.cll in this inftance an almoft fuflicient criterion), whence comes the azot ? At 

 firft I thought it might come from a decompofition of the alkaline bafe of the fait ; as fomc 

 chemifts h;ivc imagined tl:e vegetable alkali to be con-pofed of lime and azot : in that cafe-, 

 I expefted the reuduum would have been the fulphat of lime ; hut I found it to be chiefly 

 fulphat of potafii, with a little of the oxygenated muriat that remained undccompofeJ 

 along with it. At prefent I fliall not hazard any opinion refpefling the origin of this ni- 

 trous fmell ; but hope fome experiments I am at prefent engaged with will, if I can find 

 time to profecute them, throw fome light upon this fubje£l:. 



II. On the Detonatian and Itiflammntion of comhuflihle Subjlances -with the Salt produced by: 



FriSilon ami the Jdds. 



THE detonating properties of this fait were tried with various fubftances in the following 

 experiments : the different mixtures were intimately combined by gently rubbing them ii> 

 a ftone-ware mortar : after this was done, one fmart ftroke acrofs the mixtures would caufc 

 the whole of fome of them to explode at once, and others fucceffively by repeating the 

 friftion. The fulphuric acid inflamed moft of thefe mixtures of the fait with combuftibla 

 fubftances : the nitrous acid alfo had the fame effefl: with fome of them. 



Experiment I. ivith Phofphorus. Half a grain of this fubftance rubbed with the famo 

 weight of the fait produced violent explofion with flame. I apprehended it would be 

 dangerous to ufe much greater quantities, as the phofphorus is frequently thrown out with 

 violence before it is confumed. The fulphuric acid inflamed this mixture, as I have before 

 ftated. 



Experiment II. tuith Charcoal. Two grains of fait with one of charcoal intimately mixedi 

 and perfe£lly dry, produced by a fmart ftroke a ftrong flame without much report. The- 

 fulphuric and nitrous acids inflamed this mixture, the latter with moft rapidity. 



ExperimentWi. luith Pit-coal. A grain of 4ry pit-coal rubbed with the fame quantity of 

 the fait produced fparks and fomc fmall reports. With half the quantity of coal the reports 

 were much louder. 



The fulphuric acid added to about twenty grains of the fait with ten of the coal, prcH- 

 duced a bright red flame rifing up to a confiderable height. 



Experiment IV. tvith Sulphur. A grain of the fait rubbed with half a grain of fulphur 

 produced a very loud report, attended with flame and a itrong fmell of fulphureous acid. 

 When the fulphur was reduced to a quarter of a grain, the explofion was not made at once 



as. 



