Joulie[11] has pointed out the extreme value which may be obtained from a knowledge of the urinary constituents by the means of estimation of the acidity with suchrate of chalk. The reagent is made by slaking lime in such a way that the resulting compound is practically dry. A quantity of this--about 25 grammes--is then thoroughly shaken up with 10 per cent. solution of cane-sugar, allowed to stand, and the solution titrated against decinormal acid until it is of one-twentieth normal. The urine is then estimated directly, the suchrate is run into the 25 c.c. of urine until a faint white flocculent precipitate appears. The number of c.c. of the solution of suchrate is then noted, and multiplied by the factor of the solution. This gives the acidity related to the phosphate and other organic acid contents, and is similar to the method used to determine the acidity of wines. The second estimation consists of estimating the phosphates present by means of a standard solution of uranium nitrate, using either potassium ferrocyanide or cochineal as an indicator. The specific gravity of the urine is also determined. The result is then expressed in terms of this specific gravity, or, rather, in the terms of the density of the urine in relation to distilled water, and the whole answer returned per litre. By this method it is not necessary to obtain a twenty-four hours sample of the urine, the urine passed first thing in the morning being taken for examination. By using this density figure the quantity of acid and phosphate is expressed in relation to the density, the equation being-- The observed acidity --------------------- = Acidity per litre. The density per litre The phosphate content is expressed in the same manner, while the ratio of phosphate to acidity gives the ratio of excretion of phosphate to acidity. There is in lead-workers a considerable diminution in the amount of phosphate excreted, and, as has been pointed out by Garrod and others, lead apparently produces alteration in the solubility of the uric acid content of the blood, and may therefore allow of its decomposition. Probably lead as a urate is stored up in the tissues. For further particulars of this method of the estimation of the urine, the reader is referred to “Urologie Pratique et Thérapeutique Nouvelle,” by H. Joulie.