190 MANAGEMENT OF DAIRY PLANTS 



Indiana Station • that 21 4/10 per cent of the cream- test bottles 

 used in Indiana creameries were incorrect; the maximum error 

 was 10 per cent. 



2. Inaccurate Measure or Weight of Sample. — Incorrect 

 measure or weight of samples may be due to an inaccurate 

 pipette, or to balances that are not sensitive, or to carelessness 

 on the part of the operator. 



When the sample is measured, as is done when testing milk, 

 the pipette used should be calibrated and if found correct 

 it is evident that it will measure out the correct amount, if the 

 pipette is also kept properly cleaned. The weights should be 

 tested against standard weights. It is often convenient to 

 have a standard 9 gram or 18 gram weight. This weight is not 

 used for any other purpose than that of testing the weights 

 which are in daily use. The state dairy commissioners are 

 usually willing to test weights for operators in their respective 

 states. 



Balances should be sensitive to one centigram. If the bal- 

 ances are not sensitive it usually results in too high tests and a 

 loss to the creamery. To keep balances sensitive they should 

 be properly cleaned and kept in a dry place, preferably in a 

 special case provided therefor. A balance constructed for 

 carrying several bottles at each weighing is less sensitive than 

 one constructed for carrying only one or two bottles. 



The operator when weighing out samples of cream should 

 not sacrifice accuracy for speed. It is considered that an ex- 

 perienced operator can test from 200 to 300 cream samples 

 daily and do accurate work. 



3. Improper Care of Samples. — A composite cream sample 

 should never be considered accurate unless cream from which 

 the sample is prepared is very thin. A composite sample taken 

 from cans containing cream varying greatly in fat content will 

 naturally be far from correct, as the sampler used will discharge 

 less of the richer than of the thinner cream. Furthermore, if 

 the sampler is not thoroughly cleaned each time when it is 

 brought from the rich to the thin cream, it is quite possible that 



> Bui. 145, Indiana Agr. Experiment Station, igio. 



