THE PRESERVATION OF MILK 6i 
similar results. Chittender and Gies* experimented with full-grown Dogs (in weight from 
8 to 12 kilogrammes) which were dosed during a period of from 27 to 46 days with borax and 
boric acid. They found that moderate doses of borax, up to 5 grammes daily, were without 
influence on metabolism or on general nutrition while in doses of from 5 to 10 grammes daily 
borax disturbs metabolism, increasing excretion of nitrogen and of sulphuric and phosphoric acids 
through the urine. Boric acid up to 3 grammes had no effect. Still larger doses of borax or of 
boric acid disturbed the assimilation of proteids and fats, increasing the amount of fasces and of 
their nitrogen and fat. Diarrhoea and an increase of mucous secretion were also produced. Thus 
all experimental work on the subject has been performed on adult animals. No records of 
experiments with young animals have, as far as I can ascertain, been published. Many have 
stated that the quantities of boric acid used as preservatives are injurious to infants, without 
producing direct evidence to that effect. It has been often pointed out that the average quantities 
present in ' preserved ' milks is more than the ordinary maximum British Pharmacopccia dose for 
an infant taking from 32 to 40 ounces of milk per diem. 
Most authorst are agreed that not less than 35 grains per gallon (0.05 per cent.) of a 
mixture of boric acid and borax is a minimum efficient quantity necessary to ' preserve ' milk for 
48 hours, while this quantity is rather more than sufficient for a period of 24 hours. In order to 
obtain some better indications of the probable action of boric acid on young infants and children 
I arranged a number of experiments on young kittens, 3 or 4 weeks old, just able to lap milk. 
Their condition at this age seemed more analogous to that of infants than in the case of most 
other animals, as they are entirely dependent on milk for their food until they reach the age of 
about 2 months. The experiments were made with boric acid — quantities of 40 grains and 80 
grains per gallon being employed. Judging from the experiments of Chittender and GiEs on 
adult Dogs, boric acid seems to have a less deleterious effect than borax. The experiments were 
only preliminary, and a further series, with less quantities of acid, are in progress. The animals 
were kept under the most favourable circumstances, being allowed during the greater part of the 
day to run about within a considerable area, and at night they were housed in capacious cages in 
the animal house at the laboratory. A supply of fresh milk, renewed every few hours during the 
day, was always provided. As the animals grew older a little bread was added, and later a little 
meat was also given. The results were very striking, as the following tables show. 
'American Journal of Physiology,' vol. i, 1898, No. i. f Rideal and Foulerton : 'Public Health,' May, 1899, p. 534. 
