89 



and appears ia that part of the tube which is divided into tenths 

 of cubic centimeters. 



With the aid of cold water and the water 40° C. warm, water 

 of 20° 0. is then prepared, and the lactobutyrometer is inserted 

 into this. There it remains for from one-quarter to one-half hour. 

 The layer of fat is thereby generally yet increased. 



Over the solution containing the undissolved albuminates, an 

 etheric fat solution of high refractive power has accumulated, the 

 volume of which is read by means of the divisions on the tube. 



To this end, the reading is taken from the lower meniscus at the 

 surface down to the even plane where the lower and upper liquid 

 meet. 



The amount of fat corresponding to the tenths of cubic centi- 

 meters of solution read, is found in the following tables. 



The upper portion of the lactobutyrometer contains 5 c.c. soib- 

 divided into tenths, therefore, 50 degrees. Provided the readrag 

 at the upper end (lower meniscus) had given 45° = 4.5 c.c, and at 

 the lower end of the fat solution, 31° =3.1 c.c, the height of the 

 solution would be equal to 14° = 1.4 c.c. ^ 



According to the tables we find the amount of fat = 3.991 

 per cent. 



Remark : The cleaning of the milk pipette and the lactobutyro- 

 meter is easiest effected in the following manner : Kinse first with 

 concentrated soda solution ; then with water, strong alcohol, and 

 ether, successively. 



Though this determination of the percentage of fat in milk 

 requires more manipulation and time than Feser's lactoscopic 

 method, it must be considered that this latter instrument is ex- 

 pected to give only satisfactory results, when it is' in the hands of 

 men well acquainted with analytical chemistry and the handling of 

 the apparatus. As an easy test to be used by milk inspectors, the 

 lactobutyrometer is, therefore, to be preferred. 



It requires neither special knowledge nor expertness in its use, 

 andis, therefore, always to be recommended when it is required to 

 make practically accurate determination in the shortest possible 

 time. The place of an accurate determination of the fat by chem- 

 ical analysis it can, however, not take ; bnt it will always find its 

 place of usefulness when physicians, inspectors, or dairymen desire 

 to make a fat determination, in case that the lactodensi meter test is 

 insufficient to decide the question of adulteration with certainty. 



