AGRICULTURAL CHEMISTRY — AGROTECHNY. 611 



has modified the apparatus usually used for this purpose, aud outlined a method 

 which eliminates the personal equation, so far as is practicable, in making actual 

 baking and expansion tests. " The use of a machine for mixing, the automatic 

 recording of maximum expansion in the cj'linder, and the raising of the dough 

 to a fixed height before baking all tend to render the element of judgment less 

 prominent than has heretofore been the case with most methods. Automatic 

 regulation of the temperature in the fermentation cabinet also contributes to 

 the ease of making the tests." 



The detennination of moisture in sirups by the calcium carbid method, 

 R. M. West {Jour. Indus, and Engin. CJiem., 8 (1916), No. 1, pp. 31-35, fig. 1).— 

 As the result of a study of this method the author has devised a new apparatus 

 and has made some changes in the details of the manipulation. 



It is concluded that the method is accurate within from 0.3 to 0.4 per cent, 

 and in this respect is equal to the Official Method (E. S. R., 20, p. 512). It Is 

 more satisfactory than the Official l\Iethod in that the end point is clearly 

 defined and less time is required for the determination. The carbid used 

 should be subjected to a blank test to determine its water equivalent. The 

 method is especially adapted to materials sensitive to higher temperatures and 

 to those which lose volatile substances during the usual process of drying. 

 Concordant results can be obtained with the procedure in the presence of acids 

 if a correction of the acetylene for the total acidity is made. 



The determination of reducing sug'ars. — A volumetric method for deter- 

 mining cuprous oxid without rem.oval from. Fehling's solution, F. M. Scales 

 (Jour. Biol. Cheni., 23 (,1915), No. 1, pp. 81-87). — A new volumetric method for 

 the determination of cuprous oxid in Fehling's solution is described. The 

 cuprous oxid is converted directly into cuprous chlorid, an aliquot added to 

 standard iodin solution, and the excess iodin titrated with standard sodium 

 thiosulphate. Dextrose, maltose, lactose, invert sugar, and probably other 

 reducing sugars may be estimated by this procedure. Comparable results with 

 the gravimetric method have been obtained, and only about one-fourth of the 

 time is required. 



The procedure may also be used for the quantitative determination of copper. 



Analysis of milk and milk products, H. Leffmann {Philadelphia: P. Blak- 

 iston's ^on & Co. \.1915'\, 4. ed., rev. and enl., pp. VIII-\-115, figs. 3). — This is 

 the fourth edition of the work, revised and enlarged. Analytical processes of 

 practical value are outlined in detail. 



The reaction and calcium content of milk as factors in the coagulation 

 process, T. H. Mileoy {Biochcm. Jour., 9 (1915), No. 2, pp. 215-228). — The 

 author reports the results of a number of experiments in vitro to determine the 

 influence of the hydrogen ion concentration and the calcium content of milk on 

 coagulability and digestibility. 



It is concluded that "during the course of rennin action there is no change 

 in the [H.] of milk, either in the earlier stage or in the actual separation of 

 the clot. The addition of an alkaline oxalate to milk lowers, while that of 

 CaCh raises the [H.]. Fresh milk which has been subjected to a temperature 

 slightly below boiling point for one hour shows a rise in [H.], and a fall in the 

 calcium content. Such milk is only very slowly acted upon by rennin. The 

 coagulability of heated milk may be raised either by the addition of CaCU or 

 by raising the [H.]. The former does not act simply by rai-sing the [H.], nor 

 the latter from its effect upon the soluble calcium content. The acid precipita- 

 tion zone of caseinogen lies on the acid side of the rennin zone of action, but 

 the latter gradually approaches the former as the calcium content of the mix- 

 ture is lowered, so that in all probability the latter is an extension of the 



