PRODUCTION AND CONSERVATION OF PATS AND OILS. 33 
The distinction between steam and kettle-rendered lard is not en- 
tirely one of process, as, in the packing houses, at least, only the leaf 
and back fat are kettle rendered, all the other fats going into steam 
lard. 
In making kettle-rendered lard the leaf fat is pulled from the car- 
casses while they are still warm and immediately chilled. When 
thoroughly cooled, the fat tissue is hashed fine and heated in steam- 
jacketed kettles until the clear fat, in the form of a light yellow oil 
at this temperature (250° F.), separates from the tissues. It is then 
salted and allowed to stand until the fine particles of the fat mem- 
branes separate out. Finally, after one or two more settlings, it is 
drawn off hot into the shipping packages and placed at once in a 
freezer. The cracklings left in the rendering kettle are either pressed 
to obtain the residual lard or put into the steam lard tanks. 
This rendering of lard in steam-jacketed kettles is merely a safe and 
convenient modification of the old home method of making lard by 
cooking the hog fat in a big pan over an open fire. The kettle-ren- 
dered product, therefore, has that characteristic lard flavor so highly 
prized by those who do not like the new type of lard substitutes. 
Neutral lard, or simply neutral, as the packers call it, is made from 
the first grades of leaf fat by cooking in much the same manner as 
the kettle-rendered lard. It is, however, cooked at a lower tempera- 
ture, from 126° to 128° F., so that it retains practically no hog flavor. 
It is used almost exclusively in the manufacture of oleomargarine. 
Steam lard, as its name implies, is rendered by means of live steam. 
The chopped fats are charged into large steel tanks, and after the 
cover has been fastened down live steam is turned in through pipes 
at the bottom of the tanks. When the cooking has proceeded to 
the point where the melted lard separates from the fat membranes, 
the steam is turned off and the water and solids allowed to settle, 
after which the lard is drawn off from the top and the water and 
tankage dumped out at the bottom. As some darkening of the lard 
occurs during cooking and its flavor is often too strong, it is customary 
to bleach and deodorize it by the processes already described. 
Lard oil, which is used as an illuminant in signal lights and miners' 
lamps and as a lubricant in machine shops, is made by chilling lard, 
and sometimes other fats, such as horse oil, and pressing out the 
liquid olein from the higher-melting stearin. The olein constitutes 
the lard oil. The remaining stearin is often mixed with whole lard 
to make it firmer in warm weather and is also used in making com- 
pound lard. 
INCREASING THE YIELD. 
The production of lard depends upon the weight of hogs slaugh- 
tered. As ways and means for increasing hog production in this 
country have been* fully covered in another publication of the Depart- 
