/ . 



Mr. Rigg 071 a Method of analysing Organic Compounds, 33 



that of tiie gaseous products which have passed from it, all 

 the water having been absorbed by the amianthus. 



The bent tube is at this time filled with the gaseous pro- 

 ducts of the analysis, and when the analysing tube is cooled, 

 about -,3- of its interstices are also filled with the same, and 

 this I take into account in calculating the products. 



On heating the analysing tube again, driving off all the 

 moisture, allowing it to cool, and then weighing it, I have the 

 total loss in weight to the yo^o ^* ^ g''^i"» ^^^ the contents 

 of the tube in a dry state. 



I remove the carbonic acid gas by liquid potassa, and the 

 residual gas, which is left in the small tube which is filled 

 during the latter part of the process, is first transferred into 

 the upper part of the graduated tube represented in the 

 margin *, and where its volume can be read to t-oW of 

 a cubic inch. This I calculate for as nitrogen. The 

 other residual gas is then transferred into the same tube, 

 and the volume of the two read in the centre part to 

 the 2^0 of ^ cubic inch. If no nitrogen is present in 

 the compound under examination, the volume of the 

 residual gas is less than that of the atmospheric air 

 in the oxide, together with that which had filled the 

 interstices of the analysing tube, the caoutchouc col- 

 lar, and the bent tube, and contains less oxygen. 

 The nitrogen obtained from the gaseous products which are 

 collected in the small tube, serves as a term of comparison for 

 verifying the results of the experiments which I make expressly 

 for the purpose of determining the quantity of that element; 

 and where its existence is doubtful, as, for instance, in sugar, 

 starch, &c., I first fill the tube with carbonic acid gas, use 

 black oxide of copper which has not been exposed to the air, 

 apply the ^oxne^first to the end of the analysing tube, and am 

 especially careful that no carbonic oxide is formed. 



The weight of water, and also that of carbonic acid gas and 

 nitrogen, together with their volumes, being known, this mode 

 of conducting ultimate analysis enables me to determine ac- 

 curately the quantity of water by weight, and the quantity of 

 carbon and nitrogen, both by weight and by volume, in any 

 given compound. And, further, I have the data for a very ac- 

 curate recapitulation of all the products, so as to be able to 

 speak with tolerable certainty as to the correctness or incor- 

 rectness of any experiment so made, and also for testing the 

 correctness of data already received as regards the weight 

 and volume of the different [elements contained in the com- 

 pound under analysis. 



The experiments that I have made with this simple ap- 



* Several tubes of this kind are required in order to measure the quanti- 

 ties of nitrogen contained in different compounds. 



Phil Mag. S. 3. Vol. 12. No. 71. Jan. 1838. F 



