AGRICULTURAL CHEMISTRY AGROTECHNY. 503 



The edible qualities of the fruit are not impaired if it has not been fi-ozen so 

 severely as to cause it to dry up. 



The examination of a sediment found in "Alpine milk," M. Sato (Trans. 

 Sapporo Nat. Hist. Soc, 5 (1915), No. 3, pp. 190-192). — On opening a can of con- 

 densed milk a small, white, amorphous sediment was found in the bottom of 

 the can which could readily be distinguished from the usual protein which 

 separates from such milks. The ash content of the material was found to be 

 46.16 per cent. The analysis of 0.26 gm. material showed the following com- 

 position : Magnesium phosphate, 0.0017 gm. ; tricalcium phosphate, 0.0486 gm. ; 

 and calcium citrate, 0.2039 gm. 



A simple method of converting the Duboscq colorimeter into a nephel- 

 cmeter, W. R. Bioor (Jour. Biol. Chetn., 22 (1915), No. 1, pp. 1^5-149, figs. 2). — 

 The method is described in detail and illustrated by charts. 



Contribution to the titrimetric determination of ammonia according to 

 Winkler's method, E. Bernard (Landw. Vers. Stat., 86 (1915), No. 5-6, pp. 331- 

 337). — The method of Winkler for the titrimetric determination of ammonia 

 (E. S. R., 31, p. 108) has been slightly modified by using a 5 per cent solution 

 of boric acid in place of a 3 per cent solution as originally recommended. 

 Methyl orange was used as an indicator in preference to Congo red, as the color 

 change was found to be sharper, especially when titrating with normal hydro- 

 chloric acid. The experimental results of a series of protein determinations 

 in feeding stuffs, comparing the modified method with the standard Kjeldahl 

 method, are given. Very close agreement between the results of the methods 

 is indicated. The author concludes that the modified method is superior to the 

 Kjeldahl method in its practical application and rapidity in protein deter- 

 minations. 



A simple method for the determination of small amounts of potassium, 

 H. J. HAiiBURGER (Biochem. Ztsclir.,11 (1915), No. 6, pp. 415-463).— The author 

 describes in detail a procedure for the determination of small amounts of 

 potassium, which depends on the volumetric determination by centrifugation 

 of the crystalline precipitate of potassiumsodiumcobaltinitrite (Co(N02)3). 

 3(KNa(NO,).)+nH20). 



A special form of centrifuge tube is described in which the volume of the 

 precipitate is measured. The capillary portion of the tube is divided into 100 

 parts, each division representing 0.0001 gm. of potassium. The experimental 

 error is always within one division on the scale, whether the amount of potas- 

 sium in the original solution be large or small. 



The presence of a large amount of sodium or of calcium, magnesium, and 

 sulphates does not influence the results, but phosphoric acid, except in very 

 small amounts, interferes and must be removed. This is accomplished by 

 precipitation with a solution mixture of calcium chlorid and calcium hydroxid, 

 or, more advantageously, with magnesium mixture. Advantages over the 

 chloroplatinate and perchlorate methods claimed are those of rapidity and 

 convenience, greater accuracy and the use of less material, the absence of 

 any interfering substance except phosphoric acid, which is easily removed, 

 and little preparation of the sample for the determination. 



The advantages of washing precipitates by centrifugation rather than by 

 filtration are noted. 



County agents' calcimeter, J. S. McHAROt^E (Kentucky St a. Circ. 9 (1915), 

 pp. 62-68, fig. 1). — This circular de.scribes a simple and portable apparatus for 

 the determination of calcium carbonate in limestones used for agricultural 

 purposes. 



The limestone is treated with 20 per cent hydrochloric acid and the evolved 

 carbon dioxid allowed to displace an equal volume of water, which is measured 



