370 Experhnenls relative to Prussic and other Acids. 



mercurial trough, in a position declining a little from the hori-' 

 zontal one towards the table. The decomposition was then 

 commenced, by applying the flame of a spirit-lamp to the empty 

 part of the tube, and bringing it down gradually, so as to ex-' 

 plode 'n\ succession the three strata of the mixture. The ar- 

 rangement of the apparatus at the commencement of the pro- 

 cess will be instantly seen by an inspection of the annexed 

 sketch. (Plate VI. fig. 5.) 



When the retort tube was cold, it was separated, under the 

 svuface of the mercury, from the adapting tube, in such a man- 

 ner, that any gas remaining in the latter might pass up into the 

 graduated tube : tiie volume of gas collected was then ascer- 

 tained, making the necessary corrections for temperature, pres- 

 sure, and the capacity of the retort tube; after which a solution 

 of pure potash was passed up into it, and the diminution of 

 volume which it occasioned was noticed : from the gas which 

 remained, a deduction was made, for the quantity of atmospheric 

 air in the upper part of the retort tube before the combustion, 

 and which seldom exceeded -r^th of a cubic inch : the residual 

 gas was considered as azote, and found to be so by all the tests to 

 which I subjected it. The small quantity of solution of potash 

 employed to effect the absorption was then examined; and if, 

 besides carbonic acid, it was iound to contain prussic acid, I 

 concluded that 1 had not employed enough of the red oxide of 

 mercury in the combvistion, and repeated the experiment with 

 an increased proportion of it. 



iSuch was my method of effecting tlie analysis of the prussic 

 acid, and by which, as will be seen in the last line of the table, 

 I succeeded in discovering that 0'3142 gr. of it were composed 

 as follows : 



Carbon = to that in 43S9 gr. of carbonic acid, or 0-1198 

 Azote = to the weiglit of the azote gas collected (J- 1401 

 Hydrogen = to that in 07230 gr. of water . . . . 0-0843 



0-3442 

 consequently that 100 grains contain 



Carbon , . . . 34'S 



Azote .. .. 40-7 ■ 



Hydrogen . . . . 24-5 



100-0 

 Having finished my analytical investigations, I pass on to 

 the last division of my subject, which is the following compara- 

 tix'e view of the composition of the prussic, ferruretted chyazic, 

 and sulphuretted chvazic acids, and of their salts, as deduced 

 from ray analytical experiments, and as inferred from the atomic 

 theory. 



Table 



