392 DR DAVY ON THE SPECIFIC GRAVITY OF SUBSTANCES 



consolidation from a state of fusion, and the contents of which have been found 

 to be so various, and in their theoretical bearings so instructive. 



It appearing impracticable to ascertain the true specific gravity of wax in its 

 solid state in mass, recourse was had to another method. The wax was dis- 

 solved in hot alcohol, and then poured into distilled water, deprived of air by the 

 air-pump. The precipitated wax, in a flocculent state, sank in the mixture of 

 water and spirits. It was divided into three portions, to which a solution of com- 

 mon salt was added in different proportions. In the lightest of specific gravity 

 .992, at 50, the 'greater part of the flocculi sank to the bottom, or were sus- 

 pended midway; in another, of specific gravity 1.005, a considerable portion was 

 suspended midway, a little sank; and, in the third of specific gravity 1.014, the 

 greater portion rose to, or towards the surface ; a few flakes were suspended, and 

 a very few subsided. These results induce me to believe, that the specific gravity 

 of wax, free from ah*, exceeds very little that of water ; and the results of the 

 trials on the specific gravity of bleached and unbleached wax at the boiling tem- 

 perature of water, seem to show, that the former is rather the heaviest of the 

 two. 



Wax, as is now well known, is composed of two substances, cerine and my- 

 ricine. I have not examined them apart in regard to their specific gravity ; I 

 have thought it the less necessary, as the latter in bees'-wax is in small propor- 

 tion, and its specific gravity is stated to be the same as that of water, whilst the 

 specific gravity of cerine is made as low as .969.* 



Spermaceti is stated to be of the specific gravity .9433. f In connection with 

 the properties of this substance, analogous to those referred to when treating of 

 wax, there is not less difficulty in determining accurately its specific gravity in 

 mass. At the boiling point of water, I find its specific gravity to be .839 ; at 100, 

 which is about 12 below its point of congelation, it appears to be about .910 ; and 

 at 50, apparently .96, using the same method as that employed with wax. This 

 last number, as in the parallel instance of wax, and for the same reasons, is, I be- 

 lieve, too low. I find, that when spermaceti is dissolved in hot alcohol, and is pre- 

 cipitated by admixture with water freed of air, that the flocculi thrown down 

 are suspended when a solution of common salt is added in just sufficient quantity 

 to make the specific gravity of the mixture that of distilled water ; and which, 

 therefore, probably, apart from entangled ah*, is the true specific gravity of this 

 substance, and also of cerine, of which the purified crystalline spermaceti, the sub- 

 ject of trial, almost entirely consists. 



The specific gravity of cholesterine is commonly considered inferior to that of 



* Noveau Syst&me, de Chimie Organique, par F. V. RASPAIL, iii. 406. 

 t HENRY'S Chemistry, 6th edit. ii. 505. 



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