PURIFICATION OF FISH-OIL. 



and arc very Their great ufe in the edalcoration of fifti-oil arifes, there- 



|f f |£ e in J Ur,fy " fore > from their converting fuch parts of the gelatinous fluid 

 and bile as are highly putrefied, inftantly into volatile falts, 

 and caufing a rapid putrefaction of the other parts ; by which 

 but they do not means the oil is freed from them by their diflipation. They 

 remove empy- j not ^ h ovvever> equally act on the parts of the oil on which 

 the empyreumatic fcent depends, unlefs by the afliftance of 

 heat; for when they are commixed with the oils without heat, 

 in proportion as the putrid fmell diminilhes, that becomes 

 more fenfibly prevalent. The ultimate a6tion of lixiviate 

 falts on animal oils, except with refpect to the empyreuma, 

 feems to be the fame either with or without the medium of 

 heat j for the fame urinous and putrid fmell, gradual diminu- 

 tion of the colour, and fetid fcent, happens in one cafe as in 

 the other, except with regard to the acceleration of the 

 changes ; and fuch falts, where the purification is required 

 to be made in a great degree, are a neceflary means, as they 

 are more effectual than any other fubftance that can be em- 

 ployed. 



The ufe of lixiviate falts alone is not, however, the moft 

 expedient method that can be purfued for the edulcoration 

 of oils, for feveral reafons. If they be ufed alone, cold, in 

 the requifite proportions, they coagulate a confiderable part 

 of the oil, which will not again feparate from them under a 

 very great length of time ; and when they have deftroyed 

 the putrid fcent, a ftrong bitter empyreumatic fmell remains. 

 The fame inconvenience, with relation to the coagulation of 

 part of the oil, refults when they are ufed alone with heat. 

 The fuper-addition of common fait, (which refolves the 

 coagulum and counteracts the faponaceous power of the 

 lixiviate fait, by which the oil and water are made to combine) 

 is therefore neceflary ; and the expence arifing from the larger 

 proportion of lixiviate fait, requires it to be employed if no 

 Alkaline earths, other alkali be taken in aid, and renders the junction of alkaline 

 earths with it extremely proper in the edulcoration of oils 

 Lime >s good but for commercial ufes. Lime has alfo an edulcorative power 

 it coagulates. on an ; ma { j| s . ? t j t h as a jf f ft rori g a coagulative aftion, 



that the additio M of a large proportion of alkaline falts be- 

 comes, when it is ufed, neceflary to reduce the concreted 

 dil to a fluid ftate ; and therefore this fubfbmce alone is not 

 proper for that purpofe. The combination of lixiviate fait 



with 



The alkaline 

 carbonates 

 render part of 

 the oil folid j 



but this is cor- 

 rected by com- 

 mon fait. 



as do alfo foap 



