Mr Davidson on the Adulteration of Fixed Oils. 253 



mixed M'ith 90 grs. of Levant olive oil, and afterwards treated 

 with Vs of the acid nitrate of mercury, the whole was solidi- 

 fied in seven hours, but the consistency was much softer than 

 that of pure olive oil treated in the same manner. I have 

 treated many varieties of olive oil with the acid nitrate of mer- 

 cury, and find that the consistency in general is nearly that of 

 strong citrine ointment, but have never found any of them so 

 soft as the portion that was falsified with rape oil ; but this 

 difference of consistency ought not to be depended on, un- 

 less a comparative experiment be made at the same time with 

 pure oil of olives. Although both oil of almonds and castor 

 oil are solidified by the acid nitrate of mercm-y, there is little 

 probability of their being employed to falsify oil of olives, on 

 account of then* higher price. The appearance of the oil of 

 almonds, when solidified by the acid nitrate of mercury, is 

 very similar to the oil of olives treated by the same reagent, 

 bat it is much softer in consistency. Oil of almonds is also fre- 

 quently adulterated, and I find that the acid nitrate of mer- 

 cm-y may be employed to detect the presence of some foreign 

 oils in it. 10 per cent, of rape oil, added to oil of almonds, 

 prevents the complete solidification, and a small portion re- 

 mains fluid, on the top, of a brown colour. 20 per cent of oil 

 of poppies, added to oil of almonds, prevents nearly altogether 

 the solidification, the greater part remaining fluid of a brown 

 colour. 



Castor Oil is solidified very slowly by the acid nitrate of 

 mercury, requiring two or three days to complete it ; but, in 

 the course of eight or ten days, it becomes as hard as pure 

 oil of olives treated in the same manner, and has a peculiar 

 odour. As neither M. Poutet nor M. F. Boudet have made 

 any researches w'ith regard to the action of the acid nitrate 

 of mercury, or hyponitrous acid, upon fish-oils, I made the 

 following, as well as the preceding experiments, in July and 

 August 1834. 



Dolphin Oil, of a pale citrine colour, and having nearly as 

 little fi.sh odour as sperm oil. — 120 grs. of this oil were mixed 

 with 10 grs. of the acid nitrate of mercury, in a half-ounce 

 j)hial and frequently agitated, according to the method of M. 

 Poutet. In a few minutes, it becauu> of a milky colour, was 

 VOL, i.vi. NO. xxvin. — AIM! 1 1. 1840. s 



