252 Ml' Davidson on the Adulteration of Fixed Oils. 



which exists in it ; and he found that one part of this agent is 

 sufficient to transform 200 parts of olive oil into a solid 

 body.* He prepai-es hyponitrous acid by distilUng the nitrate 

 of lead, and, on account of its volatility, he adds three parts 

 of nitric acid sp. gr. 1.350 to give it fixity. He has also found 

 that the following oils are solidified by the hyponitrous acid, 

 viz. the oil of the sweet and bitter almond ; the oil extracted 

 from the nut of the Corylus avellana; the oil of the Anacardium 

 occidentale ; castor oil, and the oil extracted from the seeds 

 of the Brassica campestris. M. Boudet is of opinion that the 

 siccative oils may be distinguished from the non-siccative by 

 the hj'ponitrous acid ; for, with the exception of castor oil, 

 the siccative oils resist its action, while those which are non- 

 siccative are solidified by it. He calculates the proportion of 

 adulteration by the retardation of the solidification. Thus, 

 in mixing 1 gr. of hyponitrous acid with 100 grs. of oil of 

 olives, he has remarked that the solidification was retarded 

 forty minutes by ihr, of oil of poppies; ninety minutes by 

 5^ii, and a much longer time by I'o- 



He recommends that, as it is difficult to place the oils al- 

 ways in the same conditions of temperature, and when exact 

 results are wanted, that pure oil of olives should be tested witb 

 the reagent at the same time, and even mixtures of it and 

 oil of poppies, in order that they may serve as a means of 

 comparison . 



I have repeated most of the experiments of M. Poutet, 

 and find that the acid nitrate of mercui'y is a good practical 

 test for ascertaining the adulterations of olive oil with oil of 

 poppies and linseed oil ; but cannot be considered so certain 

 with regard to its falsification with the common rape oil of 

 commerce. I find that rape oil is solidified by the acid ni- 

 trate of mercm'y in two or three days to the consistency of 

 thick honey, and has a deep orange-brown colour ; and M. F. 

 Boudet states, that the oil exti-acted from the seeds of the Bras- 

 sica campestris is solidified by the hyponitrous acid. In or- 

 der, however, to ascertain the effect of a small adulteration, 

 the following experiment was made. 10 grs. of rape oil wiere 



■ — — ^ u ll;lli<[ 



• Annales de Clumic et de Pliysique, Aout 1832. r . . . q , 



