Total receipts over all roads for the year ending December 31, 1885.

METHODS OF ANALYSIS.

A careful study of the question during the past year leads me to conclude that Waller's method of milk analysis, as given in the report of 1884, is the best.

The American Society of Public Analysts inquired into the matter and found that Waller's method was generally used in this country.

An experience of some six years has led me to conclude that this method is in every way satisfactory; as the whole operation is conducted with the minimum amount of manipulation.

In regard to the analysis of condensed milk the method given in the report of 1884 seems to answer all purposes and to be a rapid and accurate one.

No new methods of detecting other adulterations have come under my notice. A test for the presence of water is described in the Analyst, vol. X, p. 146, J. Uffelman, and consists in placing in a porcelain capsule a few drops of a solution of diphenylamine in concentrated sulphuric acid; upon adding a few drops of the suspected milk a blue color will form if the milk contains water. This arises from the fact that all water contains more or less nitrates. These nitrates form with the diphenylamine a deep blue color.

This test is too delicate, however, for practical use; if we merely rinse out a car with water, allow it to drain say for twenty minutes, and then fill it with pure milk, a few drops of this milk will show a decided reaction with the diphenylamine.

TESTING MILK.

Many experiments were made on the methods of testing milk during the past year in order to arrive at some practical method for the use of milk producers and buyers. The lactometer and lactoscope (Fesers) seemed to be the instruments best fitted for the use of practical men. The lactometer to determine the specific gravity and the lactoscope to determine the percentage of fat. The usefulness of this last test is shown in the tables of the dairy inspections, for it will be seen that in each dairy there are a number of cows giving milk rich in fat, and it can readily be understood that with a little attention the cows in the dairy could be separated into cheese, butter and milk cows.

METHODS OF TESTING.

The fact that the specific gravity of milk is an indicator of the per cent of its constituents, more particularly the amount of water, has been a subject of discussion for some time past. That a large percentage of cream will reduce the specific gravity, provided that the solids not fat, viz.: caseine, sugar and salts, remain the same, is un

doubtedly a fact, but it must be taken into consideration that milk rich in fatty matters is usually rich in solids not fat. It must be distinctly understood that we speak of the average milk and not of isolated

cases.

The testimony given in the Schrumpf case shows conclusively that the average milk has a specific gravity greater than one hundred degress on the lactometer whose one hundred point indicates a specific gravity of 1.029. The endeavor to disprove this fact by the testimony for the defense showed the extreme difficulty in finding isolated cases of a single cow giving milk of a specific gravity less than 1.029. From reliable sources it has come to my knowledge that the experts employed for the defense spared neither time nor money in the endeavor to find milk, no matter of what quality, whose specific gravity was less than 1.029.

The results given below of many hundred tests made by the experts of this commission show conclusively that not only does the average milk of a dairy have a specific gravity greater than 100 degrees at 60 degrees Fahrenheit, but that milk from single cows nearly always has a specific gravity greater than 100 degrees at 60 degrees Fahrenheit.

A chemist who pretends to learn or know any thing about milk by study in his laboratory alone must be classed as one who still has to learn the rudiments of the subject. The only possible way to obtain a knowledge of this subject is for the investigator to spend a large portion of his time among the milk producers.

The practical knowledge thus obtained enables him then to theorize on the subject. To my mind the practical information to be obtained from the farmers of this State on the subject of milk cannot be overestimated, and the opinions of any chemist or expert on many matters relating to milk are absolutely worthless without such practical knowledge. It has become a matter of considerable importance for the milk producer to determine the quality of the milk produced, not only from his dairy, taken as a whole, but from each individual of it.

The little attention paid to this subject is shown on reference to the results of the inspection of dairies by this commission in various sections of this State, for out of each herd whose milk was tested it is seen that a few of the cows at least produced milk whose quality was almost equal to the average Alderney.

Now a farmer who would test the milk of each cow and by this means separate the herd into two classes, first, butter cows, second, milk cows, would certainly be the gainer.

The instruments designed for this purpose are simple in construction and easily used.

1. The Lactometer.

This should be used as follows: Cool the milk to 60 degrees Fahrenheit. Float the lactometer in the liquid, being careful not to wet that part of the stem of the instrument above the surface of the milk, and note the point at which the instrument floats.

2. The Lactoscope.

The lactoscope is an instrument, see First Annual Report, page 90, which indicates the per cent of fat in the milk; and the results ob

tained by it depend upon the fact that the color of the milk is due to the globules of fat which the watery part holds in suspension. See plate 1 of First Annual Report.

Now it can be readily understood that if we add water to milk the opacity will grow less and less as the amount of water is increased, because the fat globules are spread further and further apart; or in other words, if we add a quart of water to a quart of milk, the fat globules contained in the quart of milk are now mixed through the two quarts of milk and water, and therefore the milk is only half as opaque as before the water was added. In the same way enough water could be added so that the milk would become almost transparent.

The lactoscope depends then on this principle and is used as follows: Add the milk from the measuring pipette in the manner directed; then add small quantities of water, shaking each time. After the addition of the water hold out at arm's length and determine if the black lines on the white glass stem can be seen. Continue this addition of water until the lines can be seen through the mixture of milk and water. Then note the per cent of fat indicated on the side of the instrument at the point to which the mixture of milk and water has risen.

This will be the per cent of fat contained in the sample of milk tested. A few examples of the amount of fat found by the lactoscope compared with that found by analysis will be of interest.