OF THE FIXED OILS IN CONTACT WITH SULPHUR. 365 



sustained, the frothing and evolution of sulphuretted hydrogen continue, and at 

 the same time, an oil of a peculiar disgusting odour, resembling that of garlic, 

 but more disagreeable, passes into the receiver. 



In the investigation of the products of this action, the first and most essen- 

 tial step was to determine the particular constituents of the oil from which they 

 are derived. In order to do this, it was necessary to examine separately the 

 action of sulphur upon each of its components. I commenced, therefore, by mak- 

 ing use of stearic acid, which can be readily obtained in a pure state : experi- 

 ment however, shewed, that none of the peculiar products were derived from it ; 

 for when mixed with half its weight of sulphur and distilled, mere traces of sul- 

 phuretted hydrogen were evolved, and the products were identical with those 

 obtained from the unmixed acid. The nauseous smelling oils being then obviously 

 derived either from the oleic acid, or the glycerine of the oil, I prepared a quan- 

 tity of pure oleic acid, by the decomposition of the ethereal solution of the oleate 

 of lead. This, when mixed with half its weight of sulphur, and distilled in a 

 capacious retort, underwent decomposition precisely as the crude fixed oil did ; 

 sulphuretted hydrogen was developed in great abundance, and the product of the 

 distillation could not be distinguished from that which I had previously obtained. 

 I was unable to obtain glycerine in sufficient quantity to make a separate inves- 

 tigation of the products of its decomposition, but these must also be peculiar, as I 

 could not distinguish the presence of acroleine during any period of the distilla- 

 tion of an oil with sulphur. 



The product of the distillation of oleic acid was in the form of a reddish- 

 brown oil, having an extremely nauseous odour, in which that of sulphuretted 

 hydrogen was apparent. When rectified, this sulphiiretted hydrogen was driven 

 off, and the first portions which distilled were perfectly transparent and colour- 

 less. As the process continued, however, the products became gradually darker 

 in colour, and the last portions which distilled became semisolid on standing, 

 from the deposition of a quantity of white crystalline plates. These were sepa- 

 rated by filtration through cloth, expressed strongly, and purified by successive 

 crystallizations from alcohol, until they were entirely free from smell and colour. 

 The product was then in the form of white pearly scales, which possessed acid 

 properties, and were totally insoluble in water ; they were not therefore sebacic 

 acid, no trace of which could be discovered among the products ; but, on the con- 

 trary, possessed all the properties of margaric acid. These crystals were obtained 

 from quantities of oleic acid, prepared at different times, and with the greatest 

 possible care, and must have been formed during the decomposition. In order, 

 however, to set this point at rest, some of the same oleic acid was distilled alone, 

 when abundance of sebacic acid was obtained, and the latter portions of the rec- 

 tified product did not deposit any crystals on cooling, but remained perfectly 

 fluid. As this solid acid is produced only in compai'atively small quantity, and ■ 



