376 Pyi'oxylic Spirit and its Compounds. [Nov. 



hydrogen, and IJ chlorine, containing half an atom more 

 chlorine than the chlorhydrate of methylene of Dumas, 

 tvhich was prepared by heating a mixture of 2 parts of 

 common salt, 1 part of pyroxylic spirit, and 3 parts of con- 

 centrated sulphuric acid. 



2. Dihydrate of Carhydrogen. — If 1 part of pyroxylic 

 spirit be distilled with 4 parts of sulphuric acid, a similar 

 appearance is presented as when alcohol and concentrated 

 sulphuric acid are distilled. During the whole process 

 much gas passes over, containing sulphurous and carbonic 

 acids, which may be removed by caustic-potash. A gas then 

 remains, which is absorbed by water, possesses an ethereal 

 odour, and burns with a flame like that of alcohol. It is a 

 dihydrate of carhydrogen, or the hydrate of methylene of 

 Dumas, and bears the same relation to pyroxylic spirit that 

 ether does to alcohol. It required 3 vols, oxygen to burn 

 it. Its density, by experiment, was 1*617, which corre- 

 sponds nearly with, 



2 vols, carbon . . . . = -8332 = 2 atoms . . 1*5 

 2 vols, hydrogen . . . -1389 2 atoms . . -25 

 1 vol. vapour of water . '6250 1 atom . . 1*125 



1*5972 2*875 



Hence, its composition is exactly the same as alcohol, in 

 so far as regards the proportions of the elements ; but it is 

 obvious, from the difference in their properties, that the 

 elements are differently arranged, the dihydrate of carhy- 

 drogen being 2 C H + HO. 



The dihydrate is a colourless gas, with an ethereal smell, 

 and does not liquify when cooled to — 16° (3°i F.) Water 

 dissolves about 37 times its volume at the temperature of 

 18'^(64°J), and acquires a smell of ether, and a taste of 

 pepper. Alcohol dissolves it in greater quantity. Sulphuric 

 acid dissolves much of it, and abandons it when diluted 

 with water. It is but justice to state that Macaire and 

 Marcet discovered this gas. It is always a subject of regret 

 to see one man undervaluing the labours of another. Dumas 

 and Peligot have, in the present and preceding instances, 

 by omitting to state the experiments of their predecessors, 

 Ijiid themselves open to this charge. We are willing to 

 believe that it is a fault of omisssion, rather than of com- 



