The sugar in milk can also be estimated by the polariscope (see under Sugar, p. 112). In case the Ventzke-Scheibler instrument is used, 65·36 grammes of the sample are weighed out and introduced into a 100 cc. flask; about 5 cc. of plumbic basic acetate solution is added, and the liquid is well shaken, and then allowed to stand at rest for a few minutes. It is next filtered, its volume made up to the 100 cc. mark, and the 20 cm. tube filled and the reading made; this divided by 2 gives the percentage of sugar in the milk. Mr. A. Adams[23] has recently proposed a method of milk analysis which consists in first placing 5 cc. of the sample in a tared beaker, and then introducing a weighed paper coil made of blotting paper from which all fatty matter has previously been removed by washing with ether. As soon as the milk is completely absorbed, the paper coil is removed and dried at 100°. The increase of weight gives the amount of _total solids_. The _fat_ is next extracted by petroleum naphtha or ether, and its weight determined. The proportion of _solids not fat_ is ascertained by again drying and weighing the exhausted coil. The standards adopted by the English Society of Public Analysts for pure milk, are:-- Per cent. Specific gravity 1·030 Ash 0·70 Solids not fat 9·00 Fat 2·50 Total solids 11·50 Water 88·50 In the State of New York, the legal standards for milk are that it shall not contain more than 88 per cent. of water, nor less than 12 per cent. of milk solids, and 3 per cent. of fat. In Massachusetts the law fixing a chemical standard of purity for milk reads: “In all cases of prosecution, if the milk shall be shown upon analysis to contain more than 87 per cent. of water, or to contain less than 13 per cent. of milk solids, it shall be deemed, for the purpose of this Act, to be adulterated.” The Board of Health of New Jersey fixes the minimum amount of total solids at 12 per cent. and the maximum amount of water at 88 per cent. In Paris, the minimum limits _for condemnation_ are the following:-- Fat, 2·70; milk-sugar, 4·50; caseine, albumen, and ash, 4·30; total solids, 11·50. The following proportion can be employed in the calculation of the amount of pure milk (_x_) contained in a suspected sample:-- From the total solids:-- 12·5: total solids found = 100 : _x_. From the solids not fat:-- 9·30: solids not fat = 100 : _x_. From the sugar:-- 4·40: sugar found = 100 : _x_. From the specific gravity:-- 1·030 : sp. gr. = 100 : _x_.