THE officials in charge of the County Technical Laboratories at Chelmsford are engaged in an investigation that will commend itself to Londoners; they are trying to gain some information as to the natural causes bringing about variation in the composition of milk. Two reports dealing respectively with the winter and summer months of the past year have been issued. From the latter we learn that in Essex milk is poorest in the months of July and August. This is the common experience of dairy farmers. It is when the pastures begin to dry up that the quality of milk suffers most. In the Essex experiments four cows were kept under observation from May until September, and two others for a shorter period. The yield of milk fell off at the rapid rate of 10 per cent, per month; with this decline there was an increase in the proportion of fat, but no regular increase in the case of solids not fat. In the month of July the percentage of non-fatty solids decreased in the milk of every animal. The milk of four of the cows, and the mixed milk of the six animals, never fell below the standard in solids not fat, but two of the cows often failed in this respect. The mixed milk and the milk of one of the cows never contained less than the standard quantity of fat, but the milk of two of the cows frequently, and the milk of two others occasionally, contained less than the required 3 per cent, of fat.