PURIFICATION OV FlSH-OIL. § 



with lime/ or the folution commonly called foap-lye, has an 

 effectual edulcorative action on fetid oils ; but it makes a trou- 

 blefome coagulation of part of the oil, if no common fait be 

 employed, and muft be ufed in fuch large proportion, if no 

 alkaline earth be added, as renders the method too expenfive. 



Lime has a power of combining with and abforbing the Lime alone is 

 putrid parts of the gelatinous fluid and bile, when commixed im P r0 P er i 

 with oil ; and effects, either with or without heat, a confider- 

 able edulcoration of fetid oils ; but it combines fo ftrongly 

 with them, either cold or hot, that the feparation is difficult to 

 be effected, even with the addition of brine ; and the oil, 

 when a large proportion of it is ufed, can fcarcely be at all 

 brought from its concreted to a fluid ftate, but by an equiva- 

 lent large proportion of lixiviate fait : the ufe of lime therefore, 

 alone, is improper, or even in a great proportion with other 

 ingredients. But when only a leffer degree of edulcoration is unlefs in fmal! 

 required, a moderate quantity, conjoined with an equal orP r .°P or j )0 " and 

 greater weight of chalk, which affifts its feparation from the 

 oil, may, on account of its great cheapnefs, be employed very 

 advantageoufly : it will in this cafe admit of precipitation from and brine, 

 the oil by the addition of brine. It may be alfo expediently 

 ufed, when lixiviate fait is employed with heat for the moll: 

 perfect purification of oils ; for it will in that cafe give room 

 for the diminishing of the quantity of lixiviate fait, though the 

 proportion be neverthelefs fo reftrained as not to exceed what 

 the proportion of lixiviate fait (juft requifite for the edulcora- 

 tion) can feparate from the oil. 



Chalk has an abforbing power fimilar to lime, but in a lefs Chalk lefseflet- 

 degree on the putrid fubftance of oil ; it does not, however, tual » but "J a y 

 combine fo ftrongly with the oil as to refift feparation in the ot hcr matters. 

 fame manner, and is therefore very proper to be conjoined 

 either with lixiviate falts or lime,, as it renders a lefs quantity 

 of either fufficient, and indeed contributes to the feparation 

 of the oil from them. 



Magnefia alba or the alkaline earth which is the bafis of the Magnefia and 

 fai catharticus, and the Angular earth vvKv. is the bafis f alu ™ flere J eaed - 

 alum, both have an edulcorating power J fetid oils; but, 

 like lime, have too ftrong an attraction with ihem to be fepa- 

 'rated fo as to admit of the reduction of the oil from the con : 

 creted ftate to which they reduce it ; and therefore, as they 

 are not fuperior in efficacy to lime and chalk, but much dearer 



3 or 



