Page:Science vol. 5.djvu/147

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�� ��G. L. Higby gave an average specific gravity of 1.0295. Two samples of a Jersey cow's milk sent by the commisaioner of agriculture miu-ked 1.033. The milk from Mr. W. Blair, of a cow fed priucipally on ensilage, twenty- two samples, gave speeiQc gravity 1.0318; Mune cow f«l "chop food,' fifteen analjses, 1.310. It is a very common practice to re- move the cream, and then add water until the milk is reduced to its original density. For this reason the use of the lactometer for deter- mining the purity of milk may lead to serious error. It is also true that perfectly genuine milk may vary greatly in density. The first t>( the milking is always poorer in cream, and therefore denser, than the last. Unless, there- fore, the conditions under which the sample of milk is obtained are known, the number ex- pressing its density is not conclusive in respect to its genuineness.

The volume of cream which a given milk will kfford depends on many conditions. Tmns- 'portatioQ. shape of vessel, temperature, and time allowed for cream to rise, are the chief causes which aSect the cream volume. A re- markable decrease in the volume of cream has also been noticed In milk samples purchased in open market. Thirteen samples bought in open market showed a percentage of cream of seven. Thirty-four sam|)les bought of the dairyman, and known to be genuine, gave fif- teen per cent of cream by volume. This euri-

s phenomenon will certainly be of interest

mi Ik- buyers.

The fat in a milk is not always in proportion to the volumetric percentage of cream : there- fore the determination of the fat (ether ex- tract) gives a better index of the butter-making value of the milk than is alforded by the vol- of the cream alone. In a hundred and seven analyses the average percentage of fat vas Dearly five.

The sngar is the most constant constituent

milk. Over two hundred analyses show an

iTeragc percentage of sugar of milk of four

id six-tenths. Its determination optically is

ick and accurate. It is the safest single eri- irion by which to judge of the purity of the

mplB.

The caseine of milk is composed of several Albuminoids. No attempt at separation of these bodies has been made. The average percentage of albumens in American milks is markedly less than in those of other countries. In the analyses made, the average per cent is nearly three tind a half. These analyses sfaow that the milks of the United States are

■tter adapted for butter than for cheese mak-

��ing. They are cimvaclerized in general by a large percentage of fat and sugar, and a lower content of albumen, than the milks of Europe- It is the intention of the bureau to extend these analyses so as to determine the localities of the country where the best milks arc produced, to note the influence of change of season on the composition of the milk, nud to carefully study the characteristics of the milk of differ- ent breeds of cows, and the influence of vari- ous foods thereon.

lluch of tl)e value of analytical work on milk which is done in this country is lost on ac- count of the many different methods of analy- sis employed. These diflTcrent methods render it impossible to compare the work of various analysts. The bureau hopes also, by a patient trial of all the most approved methods, to be able to unite the analysts of the country on that procedure which a large experience may pronounce the best. II. W. Wilev.

��So few earthworks resembling animals in their shape are known beyond the liraitB of Wisconsin, that I send you an account of several which I have discovered during the past two seasons, the majority of which are situated south of St. Paul, twenty-five of tliem being in this state.

In the diagrams accompanying this article, I have shown the outlines of a few of the most interesting of these Minnesota efligy mounds, and here give a short description of each, with its surroundings. They are all reduced to the same scale. 1 : 500.

No. 1 is situated near the village of La (.'resccnt, and probably represents a frog. Its greatest length is ninety-eight feet. The body is two feet high, and the head eighteen inches. Near it is a bii-d-efflgy ; and within a quarter of a mile there are five other bird-efligies, with sixty-nine round mounds and embankments. The frog is on a terrace about fifty feet above the Mississippi Uiver : and part of the mounds are on the lower terrace, which is about thirty feet above the ri^'er.

No. 2 is on the town site of Hokah. It is situated on a terrace some seventy feet above Root River, Fi-om the extremit,\' of the snout to the tip of the tail, its length in a right line is just sixty-two feet and a half, and the body is a foot and a half in height. There are two bird-elfigies on a terrace some ten feet below this one. Formerly there existed sev-

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