70 BOAED OF AGRICULTURE. 



than the milk wc know to be pure, we will let the man go. 

 Every patron taking his milk to that factory is his debtor ; he 

 is bringing better milk than the others, and was suspected of 

 evil on account of his goodness. It would be cruel to pursue 

 him any further ; but we could all of us take that man by the 

 hand and give him a hearty shake, and he would always be 

 able to look us square in the eye. But we will suppose that 

 he does not have more than half as much cream on his milk 

 as there is on the sample which we know to be pure ; then, 

 when the cream is taken oif, we drop this "little joker" into 

 his cream gauge, and see where it settles, and we note that 

 spot. Then we drop it right into the other. We take this 

 per cent, glass and turn in the water until the lactometer 

 settles at the same point at which it stood in the watered 

 milk. Then we set the per cent, glass upon a level, and we 

 can look across and tell just how large a percentage of water 

 it took to water this pure milk so as to have it precisely like 

 that which had been watered "before. In this way we can tell 

 just how large a percentage of water it had. If I have not 

 made this plain to you, say so, and ask any questions that 

 may occur to you. 



Question. When pure milk varies from 1000 to 1008 

 and 1032, how are you going to tell whether that is pure milk 

 or milk and water? 



Mr. Lewis. I have not found that variation. The great- 

 est variation that I have been able to find in the whole range 

 of milk is from 1020 to 1044, and when you bring it down to 

 percentages it is a variation of less than 2.4 per cent, in the 

 whole chiss of milk. It is astonishing that milk is so nearly 

 alike, and yet so different. You feed the young of one class 

 ■ of mammals upon the milk of anothcn-, and see how greatly 

 the results will differ, and yet how nearly alike milk is ! I 

 would say, that we obtain the specific gravity of milk (most 

 of you will know this better than I) by weighing a cubic foot 

 of it. Now, a cubic foot of water, which is the standard of 

 specific gravity, or the standard by which we compare all 

 others, not only liquids, but solids, is simply this : a cubic* 

 foot of pure water, at a temperature of sixty degrees Fahren- 

 heit, when the barometer will stand at thirty inches, will 

 weigh precisely a thousand ounces avoidupois weight. A 



