374 MR SCHMIDL ON THE CONSTITUTION OF OIL OF CAJEPUT. 
this secondary product, I hope to be able to give some further and more satis- 
factory results about it in a subsequent paper. 
II. MonoHYDRATE OF CAJPUTENE.—C,, H,,+HO.* 
The crude oil is raised to its boiling point in a deep open vessel, and when com- 
mercial sulphuric acid is continuously dropped into it, violent ebullition—which 
after a short time is accompanied by a peculiar crackling sound—takes place. 
As soon as this is observed the flame is lowered, and the acid very cautiously 
added, until almost suddenly the fluid assumes a dark colour, which goes on in 
one moment from the surface throughout its whole depth. Should this be over- 
looked, and the acid indiscriminately added, the process goes on further than 
desired, sulphurous acid is formed, both equivalents of water removed, and 
the products become very complicated. At the moment, therefore, when the 
darkening of the substance just commences, the vessel must be removed from — 
above the flame and allowed to cool. The upper oily fluid is then separated from 
the acid, well washed and distilled. Amongst the fractions obtained thereby, I 
chose that which passed over at 170° to 175° C., as having been the largest; and 
after several rectifications, I proceeded to ascertain its composition, and to de-— 
termine the density of its vapour, of which the following are the details :— 




(a) 3°75 grains of substance gave, . : 11:38 CO, 4:00 HO. 
(b) 8-45 ? ; ey? ll oey-Ca., 3°59 HO. 
(c) 2:04 . 3 beats 618CO, 2180 HO. 
Carbon, ‘ , 82°73 82-79 82-62 82°75 
Hydrogen, : ; 11:85 }a 11:59 >b Bee 11:72 } Theory. 
Oxygen, aE 5-42 5-62 5:51 5:53 
100-00 100-00 100:00 100:00 
Vapour Density. 
1: 2. 3.) 
Temperature ‘ eh 18° C. Temperature Se ay LO2C. Temperature “ air, 20° C. 
Temperature of vapour, 220° C. | Temperature of vapour, 210° C. | Temperature of vapour, 200° C. 
Excess of weight, 0°404 grm. Excess, 0'°405 grm. Excess, 0°520 erm. 
Capacity, 159-5 CC. Capacity, 158-4 CC. Capacity, 214 CC, 
Residual air Residual air, 2 CC. Residual air, 14, CC. 
Barometer, 750 M,M. 
D==5:19, D=5:26, D=5'27. 


* Since April last, the time when the present paper was read before the Royal Society, I 
undertook, at the suggestion of several professicnal friends, to prepare anew the substances under 
consideration. The results arrived at now, by repeated combustions and determinations of its vapour 
density, showing nowhere a difference of much more than one-tenth, if compared respectively with 
one another, or with those obtained previously, leave really little or no doubt at all about the purity 
and chemical unity of the substance—however novel, singular, and exceptional it may seem, that the 
vapour of a body containing one atom of oxygen should condense to four volumes, However, as the 
substance is easily prepared, the experiment should be repeated by others, and not only with Oil 
of Cajeput, but with all the bihydrates of the turpentine-radical: Like experiments with bodies of ana- 

