45, CORNHILL, E.C., AND 122, REGENT STREET, TT., LONDON. 185 



FIG. 482, FIG. 491. 



FIG. 486. 



* " ^ 



FIG. 489. FIG. 484. 



NEGRETTI AND ZAMBIA'S LACTOMETERS 

 FOB ASCERTAINING THE DIFFERENT QUALITIES OF MILK. 



IT is a matter of great importance in rural and domestic economy that we have a 

 ready means of ascertaining the Quality of Milk yielded by different cows. The 

 richness of milk^depending upon the quantity of oil or butter, and curd or cheese 

 which it contains, it becomes necessary that we be able to determine these quantities 

 with facility and precision. 



To attain these ends, Messrs. NEGRETTI & ZAMBRA have introduced a simple 

 form of Lactometer, by which the richness of milk may be determined by simply 

 taking its temperature and specific gravity. 



The Lactometer consists of a glass ball and stem containing a graduated scale 

 ranging from (water) to 40 Q specific gravity, adjusted to a temperature of 60 

 Fahrenheit. A Glass Jar and Thermometer usually accompany the instrument. 



482 Lactometer of a simple form for household use. The top of the scale is 

 marked O and W, indicating water, and at the lower end P signifying pure milk. 

 Intermediate between these two points are marks indicating ^ milk and f water, 

 milk and ^ water, f milk and i water. These marks must not be taken as abso- 

 lute, for pure milk will vary in quality or density according to the particular kind 

 of food upon which the cows have been feeding (fig. 482) . ' . .036 



483 Lactometer similar to above but with an additional scale on the back 

 showing specific gravity 050 



484 Lactometer, Negretti and Zambra's Lactometer of superior accuracy, with 

 absolute Specific Gravity scale, with printed instructions for use (fig. 484) 5 



