24 DAIRY ANALYSIS 



Every bottle should be read twice to make sure that 

 there is no error in the first reading. 



The following are sources of error : 



(a) Faulty graduation of the bottle ; this 



is rare. 



(6) Chemicals not equal to specification; 

 it is important that the specification for 

 these be strictly adhered to. 



(c) Insufficient mixing of the milk, acid, 

 and amyl alcohol ; this is indicated by 

 the fat being cloudy, and obstinately re- 

 fusing to become clear. 



(d) Mixing of the milk and acid before 

 addition of the amyl alcohol ; a brown 

 colour of the fat is usually found here. 



(e) Allowing a portion of the fat to remain 

 in the little conical bulb ; if the fat is 

 too low down on the scale for con- 

 venient reading, and the cork is not 

 pushed in carefully, the fat is liable to 

 jump up, as it is raised ; if the fat is too 

 high, it may partially occupy the conical 

 bulb; in each case the fat must be 

 allowed to run down before reading. 



When the corks have been used for some 

 time, they do not fit the necks of the bottles 

 FIG. 17. so well as when new, and are liable to slip 

 BottlT ou ^> anc ^ S P^ ^he acid mixture ; the times 

 when they are most liable to come out are, 

 when shaking the bottle, when removing it from the 

 disc, when removing it from the warm water, and when 

 pulling down the cork to adjust the fat layer. As acid 

 is detrimental to the clothes, always keep a bottle of 

 ammonia handy, and soak the acid- bespattered garment 

 liberally with this, should any be spilt ; if acid is spilt 

 on the hands or face, a copious stream of cold water 

 is the remedy, but do not use ammonia ; even strong 

 sulphuric acid spilt on the flesh rarely does harm if 

 washed off at once, and plenty of water is used. 



