1820.] Ferrocliyazate of Iron. 221 



ance of the experiment 14-3 grs. Now the whole water which 

 the 50 grs. of the pigment contained amounted only to 5-6 grs. ; 

 therefore, 8*7 grs. of this increase must have been matter formed 

 during the process. If we suppose the whole to be water, the 

 oxygen of it must have been derived from the peroxide of iron 

 which constituted the base of the salt. This peroxide amounted 

 to 18-9 grs. ; the oxygen of which amounts to three-tenths of 

 the whole, or 5-67 grs. 5-67 grs. of oxygen, in order to be con- 

 verted into water, must unite with a quantity of hydrogen 

 amounting to one-eighth of the weight of the oxygen, or 0*708 gr. 

 It is obvious from this that the whole of the water which could 

 have been formed during the process from the oxygen present 

 in the salt could only amount to 6*378 grs. Hence I conceive 

 myself entitled to conclude that at least 2*322 grs. of the increase 

 of weight which the muriate of lime experiences is occasioned 

 by something different from water. What this something is we 

 easily discover by performing the process without putting any 

 muriate of lime into the tubes. The liquid which comes over is 

 strongly impregnated with hydrocyanate of ammonia. How 

 much of this salt is actually formed, I had not the means of 

 ascertaining; but it must liave considerably exceeded 2*322 grs.; 

 for the iron in the residue was still in the state of oxide. Indeed 

 from the action of muriatic acid upon the residue, it was obvious 

 that it still contained peroxide of iron. 



The tubes and the glass jars standing over mercury in which 

 the gaseous products were received were coated with transparent 

 colourless crystals, which had the smell of hydrocyanic acid, and 

 which dissolved readily in water. When sulphuric acid was 

 dropped upon them, an effervescence took place, and a strong 

 odour of hydrocyanic acid was exhaled. When heated with 

 soda, they gave out a strong smell of ammonia. Hence I con- 

 sider them to have been crystals of hydrocyanate of ammonia. 



The gas extricated amounted, under the mean pressure and 

 temperature, to 46*5 cubic inches. It had the smell of hydro- 

 cyanic acid. When water was let up into it, the volume was 

 reduced to 26 cubic inches. I consider the gas absorbed by the 

 water, or at least the greatest part of it, to have been hydrocyanic 

 acid vapour ; at least the water which had absorbed it possessed 

 all the characters of Scheele's prussic acid ; which I have no 

 doubt is merely an aqueous solution of the hydrocyanic acid of 

 Gay-Lussac. 



The 26 cubic inches of residual gas were destitute of taste 

 and smell. When mixed with oxygen gas, or when brought in 

 contact with a lighted candle, this gas detonates, or burns 

 with a yellow-coloured flame. During the combustion, carbonic 

 acid gas and water are formed. The specific gravity of this gas 

 I found to be 0*8691, that of common air being reckoned 1. 



To determine the constituents of this inflammable gas, I sub- 

 jected it to a number of experiments, by burning it in a Volta's 



