42 DAIRY ANALYSIS 



is marked specific gravity (^ inch = i degree), and an 

 arrow is placed 0.14 inch from the end of the scale. 

 If the arrow is placed against the fat, the specific 

 gravity lies against the total solids ; vice versa, if the 

 specific gravity is placed against the total solids the 

 arrow will point to the fat. 



On another part of the rule is a scale for correcting 

 the specific gravity taken at any temperature to 60 F. 

 This is not shown in Fig. 25. On the rule is a scale 

 of degrees of gravity (marked lactometer degrees), and 



r. 



FIG. 27. Collins' Milk Scale 



on the slide a scale of temperature ; an arrow is placed 

 at 60 F. and this is placed against the degrees of 

 gravity found ; the temperature then corresponds to the 

 specific gravity corrected to 60 F. ; the readings from 

 the milk scale only deviate from those given by the 

 Table within the limits of reading a lactometer. 



Collins has devised a milk scale (Fig. 27) by which the 

 percentage of solids not fat can be read direct. In this 

 it is only necessary to set the reading on the lactometer 

 opposite the temperature at which the specific gravity 

 was taken, when the percentage of solids not fat will 

 be found opposite the percentage of fat. 



Though the calculation of the solids not fat or fat 

 can never be so exact as the direct estimation, it is 

 sufficient for many purposes, where small deviations do 

 not affect the conclusions drawn from the results ; this 

 method also provides a useful check on the analyses 

 where all three estimations are made, and it is hardly 

 ever found that the deviations of the calculated figures 

 from those estimated exceed 0.2 per cent. 



