SUPPLEMENT. 687 



will be shown. The lactoscope is a very ingenious instrument, and is in use at the 

 Cham laboratory, Switzerland, where the chemist had made a more perfect instrument 

 after Feser's model; but, although ingenious, it is not perfect. 



A German gentleman, Dr. Heeren, has invented an instrument which he calls a 

 "pioskop," from "pios," fat. It consists of a small round disk of india-rubber, in the 

 midst of which there is a circular raised ring, and a glass disk of the same size, also di- 

 vided by a ring in the middle, the outer part of the disk being divided into six equal 

 parts, and colored from white into shades of blue, up to dark blue. The white signifies 

 cream; the light blue, very fat; medium blue, normal; a deeper shade, less fat; deep 

 blue, thin milk; and blackish blue, very thin. In working a few drops of milk are 

 placed into the inner part of the india-rubber disk; the glass disk is next placed on the 

 top, so that the transparent part is on the top ot the milk. The milk thus squeezed 

 changes to one of the colors named above, and thus indicates its quality. Its price is 

 Is. 6<? M and is sold by Beinbauer, of Hamburg. 



An instrument called a " testing centrifuge" was recently invented by the Rev. H. 

 Bond, of Worcester, Mass. It is practically as correct in gauging the cream which is 

 contained in milk as the creamometer, but, unlike the latter, it does its work at once 

 and more completely. It is also believed to be a better test ot the availabe cream in 

 milk than analysis, because the latter gives the total butter fats, all of which have never 

 yet been obtained by any practical method of cream, separation. 



There is one more experiment which is easily performed with milk, viz, the separation 

 of the fat, and which a little practice will enable a person to do for himself. The instru- 

 ments required are a proper tube, a copper bath for the same, and a thermometer; also, 

 some ether and alcohol, both of a given strength. The tube is divided into three parts, 

 the top division being also graduated. First, new milk is poured in and up to the bot- 

 tom line, when the ether is added to the middle line, and severely shaken until com- 

 plete amalgamation has taken place. The alcohol is then added to the top line and also 

 amalgamated by shaking, a most important point. The tube is then placed in the bath 

 of water at 100 Fahr., and allowed to stand until the preparation of the fat is com- 

 plete, when it can be measured by the gauge at the top. For ordinary purposes there 

 is no better system for testing the butter-making properties of a cow. 



For the estimation of the fat, however, which is contained in milk, Professor Soxhlet 

 has invented an apparatus which is most valuable, and the best yet made for such a pur- 

 pose. By the illustration it will be seen that the stand, which is a metal one, has a 

 holder fitted with a movable screw for holding the glass tube A, to the projecting tubes 

 of which the india-rubber tubes & are attached. In the center of a is fastened a smaller 

 tube of glass, B, the top of which projects beyond a, and is closed by a cork. The diameter 

 of B must be two millimeters greater than that of the float of the aerometer. The aerom- 

 eter has a scale divided into degrees corresponding to the specific gravities, and these 

 again are divided into halves. In the float of the aerometer is fastened a thermometer, 

 graduated. An india-rubber tube connects the bottom of B with the glass tube at D, 

 which passes through the cork E of the bottle, which is designated the agitating bottle, 

 and the glass tube F, to which is attached a pair of small hand-bellows, likewise passes 

 through the cork. The stand also holds three pipettes for the measuring of the milk, 

 ether, and caustic potash. The caustic potash solution must be of 1.26 to 1.27 specific 

 gravity, which may bo prepared by dissolving 400 grams of fused caustic potash in 

 half a liter of water, which, after cooling, is made up to one liter. The ether must be 

 saturated with water, and this can be obtained by shaking commercial ether with A to 

 T 2 j of its volume of water at the ordinary temperature. A large vessel of at least 7 pints 

 capacity filled with water at a temperature of 17 to 18 C. is also required. 



To perform the experiment, the milk, after having been thoroughly mixed, and at a 

 temperature of 17. 5 C., 200 cubic centimeters are measured by the largest pipette 

 and discharged into one of the agitating bottles, which should have a capacity of 300 

 cubic centimeters. Similarly 10 cubic centimeters of the potash solution are measured 

 and discharged into the bottle containing the milk, and mixed ; GO cubic centimeters of 

 ether saturated with water are then added. The ether when measured must be between 

 16. 5 and 18. 5 C. The bottle is then closed, well shaken for half a minute, placed in 

 water at a temperature of 17. 5 C., and shaken every alternate minute for a quarter of an 

 hour. After this it stands for a quarter of an hour (although it sometimes takes a lon- 

 ger period), when a layer of the ethereal solution of fat is seen on the top, which must 

 be perfectly clear. The india rubber tube at the bottom of a is then placed in water at 

 17 to 18 C., when a is filled with the water by suction, and closed by connecting the 

 ends I V with a small glass tube. The stopper of the bottle is replaced by the cork E, 

 and the tube D is so inserted as to dip nearly to the bottom of the clear ethereal solu- 

 tion. The cork at the top of B, and the nippers, II, being opened, a quantity of ether, 

 sufficient to cause the aerometer to float, is forced by means of 41 gentle pressure of the 

 hand bellows into the tube B, when the clamp is closed and the cork inserted into B, to 



