power of the yeast. A good brewers' yeast should develop at least five grams of carbonic acid in twenty-four hours.

DETECTING CAUSES OF BEER TURBIDITIES. Turbidities of beer can be caused by:

I. Yeasts (cultivated and wild yeasts and mycoderma). 2. Bacteria.

3. Albuminoids.

4. Starch.

5. Hop-resin.

YEAST TURBIDITY.

If the turbidity is due to yeast the intensity of the turbidity is determined by counting the yeast cells by means of a hæmatimeter. The cells in the sixteen fields, each composed of twenty-five small squares, are counted, and the number of cells thus obtained is multiplied by ten, giving the number of yeast cells contained in one cubic millimeter. The counting is repeated two or three times, that is, two or three different preparations are made and the cells counted.

By means of the gypsum block culture we are enabled to determine whether the beer is infected by wild yeast or not. The presence of mycoderma is proven if, after infecting a small quantity of sterilized wort with the beer, a film is formed on the surface after the mixture has been standing two or three days at ordinary temperature. This film must then be subjected to microscopical examination, as other micro-organisms can also form films on beer or wort.

BACTERIA TURBIDITY.

In order to distinguish between bacteria and small particles of albumen present in the beer, the latter is mixed with a few drops of potassium hydrate solution and then slightly heated, when the albuminoids will be dissolved. The bacteria are then counted by means of the hæmatimeter, as when counting yeast cells.

One hundred to two hundred bacteria per cubic millimeter make the beer hazy, while 500 or more make it more or less turbid.

ALBUMEN TURBIDITY.

This turbidity is best determined by the following method: After the beer has been well shaken, it is poured into two glass beakers of 100 c.c. capacity so that it stands about one to two inches high. One of the beakers is then warmed to about 88° F. and the heated beer compared with that in the other beaker. If it has become clear, the turbidity was caused by albumen,

Beer that has been steamed at too high a temperature, very often becomes turbid by albuminoids. This turbidity does not disappear on simply warming the beer. The addition of a few drops of potassium hydrate solution, followed by heating, will in most cases partly or entirely clarify the beer.

STARCH TURBIDITY.

The cause of this turbidity is readily found by the addition of a solution of iodine. A quantity of the beer is poured into a test tube and a few drops of iodine solution added. If starch is present, the beer will appear either blue or black, according to the quantity of starch it contains. If the beer contains erythro-dextrin, the liquid will become red or brown when iodine solution is added, according to the quantity.

HOP-RESIN TURBIDITY.

This turbidity is of rare occurrence. It can easily be detected in the following way: A quantity of the beer is poured into a small glass beaker, and a few drops of alcohol or ether added. The beer is then well stirred with a glass rod. If it becomes clear, the turbidity was due to hop-resin.

LUBRICANTS AND LUBRICATION.

The question of proper lubrication of the different machines used in the brewery and malt-house, in fact, anywhere else, is a matter of no small importance.

The amount of power necessary to drive a machine, and this means the coal pile, as well as the life and proper running of the machines, is greatly influenced by proper lubrication of the sliding surfaces or bearings.

Although it is, of course, good business policy to purchase a lubricating oil, etc., as cheaply as possible, nevertheless, this striving for economy is apt to be carried too far, so that it has in many instances become a "penny wise, pound foolish" policy. A high quality lubricant can be purchased only at a correspondingly high price.

A second mistake often made is to use one kind of lubricant for too many purposes, thereby enabling the purchase of a larger quantity at one time. It is evident that a lubricant best adapted for use on shafting or heavy slow running machines is not suitable for high speed light machinery.

Another error is the application of too much of the lubricant to bearings that do not need it, or would not, if kept properly adjusted. One often finds machinery literally "swimming in oil," which is a wasteful proceeding, and should this excessive application be necessary in order to keep the bearings from heating, it is a reflection either upon the maker of the machine for accuracy and material used, or upon the skill or care of the mechanic in charge. An exception to this are tapping machines and certain types of high speed machinery the bearings of which are lubricated upon the oil-bath principle, but here special construction is provided to prevent the oil from splashing about.

The proper construction of the bearings has also a great deal to do with economical lubrication since a properly adjusted bear

ing requires less oil and will retain it longer than a loosely constructed one, the latter allowing the oil to run out as fast as it is supplied.

A considerable aid to proper lubrication is given by the oil cups with adjustable feed now in use, by means of which the oil supply can be regulated, and several hours' supply filled at one time.

THEORY OF LUBRICATION.

If two substances are rubbed against one another their motion is retarded by what is called friction. The smoother the surfaces of these substances can be made, the less friction will there be. This friction is caused by the high points in the surface of the one sinking into the depressions in that of the other and thereby retarding their motion. A surface that may appear smooth to the eye is in reality quite rough, as can be seen if a piece of highly polished steel is examined under a magnifying glass or microscope. This friction, be it ever so small in the beginning, soon becomes greater in an ever increasing ratio. This is due to small particles of the substances being broken off, and the surfaces thereby roughened, the particles assisting in further abrasion or grinding. This can be illustrated by rubbing two pieces of glass together, when it will be found that at first they hardly make any impression upon one another, but if the rubbing is continued they will become "ground" or "frosted," and a layer of powdered glass will be formed between them.

ACTION OF LUBRICANTS.

If these surfaces moving past each other can be kept apart so that their high points or ridges cannot strike against each other, it is evident that there can be no abrasion or "wear and tear." This separation is accomplished by means of lubricants, that is, substances that are viscous or "sticky" enough not to be readily squeezed out from between the surfaces, and at the same time fluid enough not to retard the motion of the surfaces. These lubricants form a thin film between the surfaces and keep them apart while moving. The lubricant must, furthermore, be of such a nature as to have no action upon the material of which the moving parts consist, for if it contains acids the latter will attack metallic parts and be likely to cause the opposite result from the one desired.

ANTI-FRICTION METALS.

If the surfaces of two substances of equal hardness rub together it is likely that they will wear equally. If on the other hand the substances are of different hardness, the softer will be the one that wears more. On this account one of the moving parts is generally made of a softer material, or, where the same material is used for both, one is fitted or lined with a softer material that can be readily removed and replaced.

In modern machinery this softer material is a metal called antifriction metal, and is principally of two kinds: bearing metal, consisting of an alloy of copper, tin and zinc, and babbitt metal, made from tin, antimony and copper.

KINDS OF LUBRICANTS.

The lubricants, or their substitutes, now in most general use can be classed as follows:

1. Mineral oils.

2. Fixed oils and fats.

3. Blown or thickened oils.

4. Blended oils.

5. Resin (rosin) oil.

6. Lubricants, containing soap.

7. Greases.

8. Solid lubricants.

MINERAL OILS.

Crude petroleum is the source of the mineral lubricating oils now in general use. Some kinds of crude oil are used in practically their natural state for lubricating heavy bearings, but the bulk of the crude oil is subjected to distillation. This furnishes an almost endless number of different products.

These products are, however, not simple substances, but mixtures of different hydrocarbons, the boiling points of which are limited within narrow confines. Out of the different products obtained the following may be mentioned:

Cymogen.-A gas at ordinary temperature, used in the manufacture of ice.

Rhigolene. Also a gas, used for medicinal purposes.

Petroleum Ether.-Liquid, boils at 160 to 190° F.; used as Solvent for fatty oils, etc.