274 Dr. Stenhouse on the Oils of Hyssop, Src, 



gravity is 0-864'5 at 56° F. Oil of laurel is accompanied with 

 a volatile acid, the quantity of which, however, is extremely 

 small. When this acid is boiled with nitrate of silver, the 

 oxide is reduced to the metallic state. The acid is probably 

 therefore the Formic. 



To prepare the oil for analysis it was distilled with water 

 to remove the resin it contained, and then rendered anhydrous 

 by fused chloride of calcium. When rectified on the oil-bath, 

 it began to boil at 301° F., but the boiling point gradually 

 rose to 325° F. It was then transparent and colourless. The 

 first portion that distilled over was set aside, but the second 

 and third, which contained nearly an ounce each, were sepa- 

 rately collected, and subjected to analysis with oxide of 

 copper. 



(1.) 0-2677 gramme, boiling at 301° F., gave 0*857 carbonic 

 acid, and 0-279 water. 



(2.) 0-2839 gramme, boiling at 325° F., gave 0-9062 car- 

 bonic acid, and 0-2956 water. 

 1. 



Carbon 88-51 



Hydrogen ... 11-57 



100-08 99-83 100-00 



It is evident from these analyses, that oil of laurel consists 

 of two or more isomeric oils belonging to the numerous tribe 

 of carburetted hydrogens of which oil of turpentine is the type, 

 containing carbon and hydrogen in the proportion of 5 to 4. 

 The action of the reagents on oil of laurel is so similar to that 

 on oil of turpentine as to render details unnecessary. The 

 reason which has induced me to change the name of oil of 

 laurel to that of laurel turpentine is, that there are two oils of 

 laurel already, one fixed and the other volatile, with which it 

 might otherwise be easily confounded. 



Oil of Hyssop, 

 The essential oil of hyssop is easily obtained by the usual 

 process of distilling the plant with water. The quantity which 

 it yields is pretty considerable. The oil has the smell of the 

 plant, and its taste, like that of the other essential oils, is very 

 pungent. When fresh it is transparent and colourless ; but 

 when kept some time, especially if the air is not carefully ex- 

 cluded, it becomes yellowish, owing to the formation of a small 

 quantity of resin. Oil of hyssop is lighter than water and 

 quite neutral ; its boiling point is not at all fixed ; it be- 

 gins to boil at 288° F., but the boiUng gradually rises till it 

 reaches 325°, soon after which it begins to pass over coloured : 



