THE CHEMISTRY OF COOKERY. 775 



A similar separation is what I suppose to occur in the cooking of 

 animal fat. I find that mutton-fat, beef -fat, or other fat when raw, 

 is perfectly smooth, as tested by rubbing a small quantity, free from 

 membrane, between the finger and thumb, or by a still more delicate 

 test of rubbing it between the tip of the tongue and the palate. But 

 dripping, whether of beef, or mutton, or poultry, is granular, as any- 

 body who has ever eaten bread and dripping knows well enough, and 

 the manufacturers of " butterine," or " bosch," know too well, as the 

 destruction or prevention of this granulation is one of the difficulties 

 of their art. 



My theory of the cookery of fat is simply that heat, when continued 

 long enough, or raised sufficiently high, effects an incipient dissocia- 

 tion of the fatty acids from the glycerine, and thus assists the digest- 

 ive organs by presenting the base and the acids in a condition better 

 fitted (or advanced by one stage) for the new combinations demanded 

 by assimilation. Some physiologists have lately asserted that the fat 

 of our food is not assimilated at all not laid down again as fat, but 

 is used directly as fuel for the maintenance of animal heat. If this is 

 correct, the advantage of the preliminary dissociation is more decided, 

 for the combustible portion of the fat is its fatty acids ; the glycerine 

 is an impediment to combustion, so much so that the modern candle- 

 maker removes it, and thereby greatly improves the combustibility of 

 his candles. 



It may be that the glycerine of the fat we eat is assimilated like 

 sugar, while the fatty acids act directly as fuel. This view may recon- 

 cile some of the conflicting facts (such as the existence of fat in the 

 carnivora) that stand in the way of the theory of the uses of fat food 

 above referred to, according to which fat is not fattening, and those 

 who would " Bant " should eat fat freely to maintain animal heat, while 

 very abstemious in the consumption of sugar and farinaceous food. 



The difference between tallow and dripping is instructive. Their 

 origin is the same ; both are melted fats beef or mutton fats and 

 both contain the same fatty acids and glycerine, but there is a visible 

 and tangible difference in their molecular condition. Tallow is smooth 

 and homogeneous, dripping decidedly granular. 



I attribute this difference to the fact that, in rendering tallow, the 

 heat is maintained no longer than is necessary to effect the fusion ; 

 while, in the ordinary production of dripping, the fat is exposed in 

 the dripping-pan to a long continuance of heat, besides being highly 

 heated when used in basting. Therefore the dissociation is carried 

 further in the case of the dripping, and the result becomes sensible. 

 I have observed that home-rendered lard, that obtained in English 

 farm-houses, where the " scratchings " (i. e., the membranous parts) 

 are frizzled, is more granular than the lard we now obtain in such 

 abundance from Chicago and other wholesale hog-regions. I have 

 not witnessed the lard-rendering at Chicago, but have little doubt that 



