- REPORT OF THE MICROSCOPIST. in Gia 
STEARIC ACID. 
The crystals of stearic acid differ materially from those of stearin. 
Pure stearic acid crystallizes quickly at ordinary temperatures. If 
a portion as small as a grain of mustard seed is placed on a slip of | 
glass and gently heated over a spirit-lamp, a thin disc of glass being 
placed over and in contact with the acid while hot and then viewed 
by polarized light, crystals may be observed shooting out in all direc- 
tions in characteristic forms. 
COMMERCIAL STEARIN. 
In the extraction of oleo oil from beef fat, or other varieties of 
fat, by means of hydraulic pressure, as in the manufacture of oleo- 
margarine, a bi-product, known as stearin,isobtained. Itis said that 
no manufacturer of good repute ever uses this crude fat in the pro- 
duction of butter substitutes, because of its indigestible character 
and for other reasons. In the course of my experiments I have found 
it necessary to examine and test samples of crude stearin. Through 
the courtesy of C. M. Vorce, esq., counselor-at-law, Cleveland, Ohio, 
I obtained recently three samples of this product, beef-fat stearin, 
bone stearin, and lard stearin. 
The difference in their hardness on being boiled and cooled is quite 
marked. Beef-fat stearin, subjected to a temperature of about 300° 
F. for a period of several minutes and then slowly cooled in an at- 
mosphere of about 60° F., becomes quite hard to the touch. Bone 
stearin treated in like manner is less firm, while lard stearin under 
the same treatment is softer than either of the preceding. The 
crystals in each case are branched and resemble those of beef fat. 
Hxtract of a letter from Mr. Vorce, member of the American So- 
ciety of Microscopists, a gentleman who has taken a great interest 
in the crystallography of fats: 
* * * Thave secured for your experiments three samples of stearin, marked 
as follows: ‘‘A. Pure lard stearin, clean and nice, fresh pressed.” ‘‘ B. Pure beef 
stearin, clean and fresh pressed.” ‘‘C. Pure bone stearin, clean, recently pressed.” 
The lard stearin I took from the hands of the stripper as he took it from the press- 
cloths. The bone stearin was pressed the day before. The beef stearin was stand- 
ing in the press when I was at the factory, and was sent over from that batch later 
in the day. Bone stearin is made from the grease rendered from butchers’ bones, 
and is composed of the marrow and hard fat together, the latter probably predomi- 
nating. The grease is grained and pressed precisely as tallow is. 
I visited all the lard-oil factories here without finding any lard stearin, as the 
oleomargarine law has killed off the lard-oil industry, except in Chicago and Kan- 
sas City. The slaughterers alone can afford to press lard. Then I tried the soap 
factories, also large consumers of stearin. None had any on hand, and are using in- 
stead the grained or crude tallow. Next I tried candle factories. None had any 
stearin except the ‘‘ refined,” which had not been bleached with acids, etc. Then I 
went for the renderers and secured the samples of lard, bone, and beef stearin I send 
you. I found out in the course of conversation with them at the Factory Rendering 
Works that the term ‘‘ grease” covers all rendered material, tallow, lard, or bone 
grease. They call the stuff before rendering tallow or lard; after rendering they 
call it grease; after pressing it is stearin. ‘‘ Fat” they apply to mixed, raw fat, 
butchers’ clippings, etc. The slaughterers have quite a different use for the same 
terms, * Be at 
CONDITION OF FATS IN HEALTH AND DISEASE. 
Incidentally to my microscopical examinations of butters and other 
edible fats, the fats and oils of many animals, wild and domestic, 
have been examined with a view to utilizing such as might be found 
