452 FOODS AND FOOD ADULTERANTS. 



shaped clusters, often with a peculiar twisted appearance. If the in- 

 dividual beef fat crystals are magnified further they still show their 

 needle-like form, but by increasing the amplification of the cluster of 

 lard crystals, shown in Fig. 2, Plate xxix, for instance, we would get a 

 similar appearance to that of Fig. 4, Plate xxx, or Fig. 9, Plate xxxin, 

 and by a still higher power the terminations of the crystals are plainly 

 shown as in Fig. 5, Plate xxxi. The differences between the typical 

 crystallization of beef and hog fat are thus easily recognized ; if DOW 

 the mixture of the two fats gave, on crystallizing, a mixture of the dif- 

 ferent forms in the proportion of the mixture, the recognition of such a 

 mixed fat would be very easy even though the proportion of the one 

 ingredient greatly preponderated. But such has not been my experi- 

 ence j instead of obtaining from a mixture of 10 per cent, beef fat and 90 

 per cent, lard, for example, a crystallization containing a great many 

 lard crystals with a few beef fat crystals scattered amongst them, as 

 shown by Dr. Belfield, I usually found a uniform kind of crystalliza- 

 tion, which varied from either typical form, but which resembled more 

 the lard. Some of these were extremely difficult to identify positively, 

 and I was obliged to recrystallize repeatedly and vary the conditions 

 before I could obtain sufficiently characteristic forms. Take the appear- 

 ance shown in Fig. 12, Plate xxxiv, for instance: the manner of ag- 

 gregation is like that of beef fat crystals, but if the individual crystals 

 are examined by a high power, it will be seen that they are not needle- 

 shaped and pointed, but plates with oblique terminations, although not 

 nearly so thin or tabular as the typical lard crystals. Most of Armour's 

 lards presented these difficulties, the appearance shown in the two fig- 

 ures on Plate xxxv being exceptional in this respect, and showing very 

 plain evidence of beef admixture. Most of them gave appearances simi- 

 lar to Fig. 12. In two of Armour's lards, viz, serial Nos. 5557 and 5559. 

 I was unable to find any evidence of beef fat admixture; the crystalli- 

 zation showing always good typical lard crystals. Compound lards 

 from lard and cotton-seed oil only would react in this way. In Fair- 

 bank's lards on the other hand, which contain a larger proportion of 

 beef fat. it is often difficult to obtain anything except the beef fat ap- 

 pearance. Pure lards sometimes give appearances, which might be 

 mistaken for beef fat. Fig. 4, Plate xxx, for example, if viewed with a 

 low power might possibly be mistaken for beef fat aggregations, but this 

 mistake need not be made if the terminations of the crystals be carefully 

 examined. The lard crystals when turned up on edge sometimes look 

 like beef fat crystals. In the examination of a sample suspected of being 

 compounded with beef fat, it is the beef fat appearance, of course, that 

 is to be sought for, unless there is some special reason for knowing 

 whether it contains any lard at all, and as soon as a characteristic beef 

 fat crystallization is observed the object of the examination is attained. 

 If none but lard crystals are observed at Hist, however, it must not be 

 concluded at once that the sample is a pure lard, but the crystallization 



