368 Further analytical ExperimeJits relative io 



I made a number of experiments upon this plan, the results 

 of which proved to me that the quantities of carbonic acid and 

 of azote gases produced, did not arrive at the maxinmm until 

 five tiuics the quantitv of red oxide of mercury contained in the 

 prusbiate had been added to it, making together six of that 

 oxide to one of prussic acid ; and that, whenever a less quantity 

 of the oxide than this had been emi)loyed, there always existed 

 in the gaseous products a portion of undecomposed prussic acid. 

 I further observed, that in al! cases the volume of azote gas ob- 

 tained was exactly equal to that of the prussic acid decomposed, 

 that the volinne of carbonic acid gas produced was invariably 

 twice that of the azote g;;s liberated in the same experiment, and 

 that the carljonic acid j^roduced accounted for only one-third of 

 the oxygen consumed. The observance of these laws by which 

 the decomposition was regulated, enabled me in constructing the 

 following table (facing page 370,) to correct the minute and 

 iniavoidable iuiiccuracies of experiment, by the superior accuracy 

 to i)e accjuired by applying to the results so obtained, the cor- 

 rections necessary to make them corresj)oud with the above- 

 mentioned laws. It enaljled me also to represent in the column 

 denoting the measures of prussic acid gas, equal quantities by 

 equal bulks ; which, for the reasons before stated, experiment 

 does not exactly show, and thus to render evident the true pro- 

 gress of its decomposition. 



It may be proper, before procediog further, to describe my 

 mode of operating in conducting the experiments from which 

 the table was compiled. This mode is similar in principle to 

 that invented by Gay Lnssac and Thenard in their Analysis of 

 Animal and Vegetable Substances, and improved by Berzelius. 

 I am greatly indebted to tli^se two French chemists for the 

 valuable information respecting this kind of analysis, which I 

 have obtained from their Eecfierches Physico- C/njmiqiies, and 

 to Dr. Berzelius for that which I have received from his paper 

 on the definite proportions in which the elements of organic 

 nature arc combined, pubiisiied in Dr. Tiiomson's Annals of 

 Philosophy for December last. It is to this information that I 

 principally attribute the success which has attended the experi- 

 ments of a similar nature which I have made. 



The method pursued by me, however, differs in several re- 

 spects from that of either of the chemists just mentioned. 



1st. In the apparatus employed, which is much more simple 

 in my process. 



' 2dly. In the nature of the oxvgenised body employed to effect 

 tire combustion. 



3dly. In the method to which I had recourse for prr>por- 

 tioning the oxygeniscd to the combustible body, by jnaking the 



former 



