Intelligence and Miscellaneous Articles. 4-75 



substance, which possessed the composition of the hydrates analysed 

 by MM. Dumas and Peligot. 



M. Deville continued the researches of M. Wiggers, and found 

 that, to obtain the hydrate of oil of turpentine in a short time, the 

 most convenient substances and proportions were, 4 litres of com- 

 mercial oil of turpentine, 3 litres of alcohol at 85°, and 1 litre of 

 common nitric acid. At the expiration of a month or six weeks 

 250 grammes of very pure crystals were obtained, and eventually 

 more than a kilogramme was gradually deposited. The oils of lemon 

 and bergamot yield the same results when similarly treated. Oil of 

 copaiba with nitric alcohol acquires much colour, and after a long 

 time yields so' small a quantity of crystals, that they could not be 

 analysed. 



If a mixture be made of oil of turpentine and crystallizable acetic 

 acid, no effect is produced even in several years ; but if a few drops 

 of nitric acid be added to the mixture, solution takes place in a few 

 days, and crystals are soon deposited. On putting the liquid in vacuo 

 over a vessel full of potash, and another full of sulphuric acid, the 

 vapour of water, of nitric and acetic acids, and of oil of turpentine 

 is absorbed, and there remains a blackish paste, from which, by means 

 of alcohol, there may be extracted crystals of the same form and com- 

 position as those obtained with nitric alcohol. 



The action of the nitric acid in the combination of water with the oils 

 it is very difficult to determine. It is to be remarked that the acid 

 does not increase the solubility of the oil in the alcohol, but on the 

 contrary, diminishes it. Neither dilute alcohol, alcohol almost ab- 

 solute, nor alcohol acidified with nitric acid, had any effect on oil of 

 turpentine after having been mixed with it for several years. Pure 

 water and these oils combine, however, though very slowly, and in 

 small quantity but regularly, in vessels in which the oils are kept 

 impregnated with moisture. The crystals thus produced, although 

 possessing the same composition as those deposited from nitric alcohol, 

 differ considerably from them in form, as will be seen hereafter. It 

 is also to be remarked, that the hydrate of oil of turpentine, which is 

 formed in a mixture of acetic and nitric acid, assumes a form which 

 is sensibly different from that which it has after solution in and cry- 

 stallization from alcohol. 



The author states that he should have been curious to examine 

 these various compounds which so resemble each other, and which 

 are perhaps dimorphous and chemically identical. Unfortunately it 

 is very difficult to procure the hj'^drate formed accidentally in old 

 oils, that is to say, the product analysed by MM. Dumas and Peligot, 

 so that all hope of obtaining it in sufficient quantity, even for an 

 imperfect examination, was relinquished. 



Hydrate of oil of turpentine is one of the most beautiful sub- 

 stances obtainable, on account of its size, perfection, limpidness and 

 splendour of its crystals, which are right prisms with rectangular 

 bases. 



This substance exerts no action on the plane of polarization ; it 

 fuses from 217° to 221°, losing a little water; when exposed to a 



