74 



IOWA ACADEMY OF SCIENCES. 



1. — Experiments in which the entire sample of milk was preserved for the time 

 named, no daily additions of fresh milk having been made. 



(rt.) With .05 per cent of Ha;Cl 2; added no correction is made for this in final 

 results. 



(fc.) With 10 per cent of HgC12 added: results corrected by deducting .05 

 per cent: 



(c.) With .65 per cent HgCl2 added, by mistake; results corrected by deducting 

 »0 per cent. 



PRESERVED. 



13.94- .60= 13.34 per cent. 

 14.06— .00= 13.46 percent. 



No. 6. 

 No. 6. 



13.47 

 13.47 



This last trial (c) indicates that the usual amount of HgCh , viz. .05 per cent, is 

 as efficient as a much larger quantity. 



(II.) Composite samples; fresh milk added each day; HgCb added .05 per cent 

 on entire composite sample. Results not corrected. 



In warm weather I prefer the use of .08 per cent or .10 per cent of HgCl2, with 

 a correction of .03 or .05 per cent. 



Lightning or Mason jars are convenient receptacles for the composite samples. 

 The mercuric chloride is weighed out and placed in the jar at the time of adding 

 the first daily sample, or before. Upon tlie addition of each daily sample to the 

 composite, the latter should be well mixed by a rotary motion — not by shaking — in 

 order to redistribute the cream throughout the whole; and this mixing should be 

 done every day, whether the samples be added every day or not. 



