Before the advent of present methods, lard refining consisted in pressing from the lard about 30 to 40 per cent lard oil, sold for lubricating and lighting purposes, etc., and mixing the stearine with straight lard, making a high grade pure lard. At this time the method of bleaching in all lard refineries was accomplished by the use of caustic soda, pearl ash, lime, alum, or other substances, the principal ingredient, being caustic soda. The underlying principle is that alkali, used in proper proportion, saponified the acid in the lard. This process, however, is a thing of the past. =Quantity and Quality.=--As shown in a previous chapter from thirteen to fifteen percent of the live weight of the hog is fresh lard, consequently where large numbers of hogs are killed the manufacture of lard is an important factor in the packing business. The principal grades are known as neutral lard, kettle rendered lard, prime steam lard, refined lard and compound lard. Tallow and stearine also enter into the manufacture of refined and compound lards. =Neutral Lard.=--When oleomargarine was first manufactured it was considered necessary to use natural butter in the mixture in order to give it the proper consistency, as the oleo oil was grainy and coarse, therefore sufficient natural butter was added to change that condition. Some one conceived the idea of using neutral lard made from leaf lard in place of natural butter in oleomargarine. When this was worked out successfully the term oleomargarine practically disappeared and the term “butterine” was substituted. In most of the butterine made today no natural butter is used. The conditions in making oleo oil and tallows have their parallel in neutral lard and kettle rendered lard. When leaf lard is cooked for kettle rendered lard, if a temperature of from 250° to 260° F. is obtained the tissues of the lard are burned or partially consumed, this heat giving it a flavor which is called “high kettle rendered” flavor. When it is made into neutral this condition is reversed, the lard being melted at a temperature of from 126° to 128° F. At this temperature no burning of tissues is possible, hence the oil extract is neutral in every sense of the word, in color, flavor and smell. With these three essential points the material readily forms the chief substance for butterine by adding milk or cream and oleo oil and cotton seed oil, as desired. =Manufacture of Neutral.=--The following steps define the process of manufacture necessary to produce neutral: _Chilling._--The leaves as pulled from the hogs are rapidly sent to a cooling room to be thoroughly chilled. The leaves are spread separately in flat sheets on metal supports, which are preferable to wood. If it is chilled too slowly a strong “hoggy” flavor is developed, which it is impossible to eradicate from the fresh product. The leaf lard should be chilled for twenty-four hours in a temperature of 32° to 34° F.