2 Dr A. Voelcker on the 



of any hygrpscopic water, by keeping it finely powdered in a 

 glass tube, at a temperature of about 230 F., and passing 

 over it a current of dry air for several hours. 



The per-centage of carbon was ascertained by burning from 

 three to four grains with a mixture of oxide of copper and 

 oxide of lead, and the simultaneous application of oxygen gas, 

 in order to secure complete combustion of the carbon. The 

 oxygen, for that purpose, was disengaged from chlorate of 

 potash, mixed with pure oxide of copper, and placed at the 

 closed end of the combustion-tube. A mixture of the oxides of 

 copper and lead possesses the advantage over pure oxide of 

 copper, of being much less hygroscopic ; for that reason it is 

 peculiarly adapted for combustions in which the exact amount 

 of hydrogen is to be ascertained. The nitrogen was deter- 

 mined according to Will and Varrentrapp's method, by heat- 

 ing the finely-powdered anthracite with soda-lime in the 

 usual way. 



For the determination of ash about 10 grains were burned 

 in a platina capsule. The ash was coloured red by oxide of 

 iron. 



The proportion of sulphur was ascertained by introducing, 

 into a red-hot crucible, a mixture of anthracite with carbonate 

 of soda and nitre, in small quantities at a time, and heating 

 the whole afterwards a little more strongly. The resulting 

 fused and perfectly white mass was dissolved in water, super- 

 saturated with hydrochloric acid, and the sulphuric acid then 

 precipitated with chloride of barium. 



According to the different results obtained, the composition 

 of the anthracite of the Calton Hill is : 



Carbon 



Hydrogen 



Nitrogen 



Oxygen 



Sulphur 



Ash 



100-00 



For comparison with this analysis, I subjoin a few analyses 

 of anthracite from different localities. 



