150 PROGRESS OF VETERINARY SCIENCE AND ART. 
Chalk, treacle, and a host of other substances have been 
supposed to be extensively in use, by some writers, without 
proof positive as to their having been discovered ; but 
they serve the purposes of rhetoric, of those w T riting elo- 
quent tracts and books on adulteration, to excite more and 
more the disgust and fears of a defrauded public. The prac- 
tice I know for a certainty to be adopted is that of extensive 
dilution, especially on Sundays, when the labourer teas with 
his wife, and when the lower classes indulge in puddings. 
By adding w 7 ater to milk, a cerulean hue is rendered distinct, 
owing to its natural opaline colour becoming more manifest, 
the dilution also detracting from its thick opaque look ; in 
fact, it looks w 7 atery. The London cow-keeper avoids this, 
by adding a little burnt sugar, which of all substances, next 
to water, is the most in use. It gives the solution a rich look, 
and counteracts the opalescent tinge. Let every one believe, 
to their consolation, that chalk mixtures entail more trouble, 
greater expense, and greater risk of detection, than simple 
dilution and innocent colouring. The mortality amongst the 
London cows, owing to improper management, is such, that 
nothing but the water-rate could save the w hole milk-vendors 
of London from becoming insolvent ; w hereas, living on the 
fruits of the latter, they thrive in business and accumulate 
riches. 
As it is my object to bring subjects up to the day I am 
writing, in noticing an article by Dr. Quidde, in the Berlin 
Magazine for last April, it is essential my readers should be 
informed of certain observations w hich have been made, and 
experiments successfully carried out, on the perversions of milk. 
It has been repeatedly observed by agriculturists, veteri- 
narians and others, that under some circumstances the milk 
of a natural aspect on being drawn from the udder, speedily 
assumes a special colour, most frequently blue; sometimes yel- 
low, green, and pinkish or red. With reference to pink milk, 
it is generally due to admixture of blood, and is therefore 
associated with a diseased condition of the mamma. Parmentier 
and Deyeux, at the latter part of the last century, after having 
fed a cow on madder for six days, saw the milk acquire a 
pink colour, and perhaps other vegetable substances of the 
kind might induce the same thing, but in a state of nature 
such cases are very exceptional, and when milk is coloured 
red, the usual unmistakeable inference is, that in it there is 
haematine. 
The blue milk, properly so called, becomes blue on the se- 
paration of its cream ; light blue specks appear on the sur- 
face of the latter, extending right and left to the complete 
