1917] AGRICULTURAL CHEMISTRY AGROTECHNY. 713 



{191 Jt), pp. 23-37; Izv. Moskov. Selsk. Khoz. Inst. {Ann. Inst. Agron. Moscon), 

 22 {1916), No. 1, pp. 23-31). — The author has investigated the conditions best 

 suited for the precipitation of phosphoric acid by calcium carbonate. Tlie 

 results show that tlie procedure depends chiefly on the temperature and 

 on the quantity and fineness of the carbonate used. The method of mixing, 

 the mechanical stirring of the mixture, the concentration of the acid In the 

 solution, and the temperature of the mixture during the reaction also influenced 

 the composition of the final product. 



The determination of phosphorus pentoxid after citrate digestion, O. C. 

 Smith {Jour. Indus, and Enyin. Cliem., 8 {1916), No. 12, pp. 1127, 1128). — A 

 method of digestion in which a clear solution (the acid treatment) is easily 

 obtained in an hour or less is described in detail by the author, at the Olila- 

 homa Experiment Station. 



On the composition and solubility of acid calciuna carbonate, A. Cavazzi 

 {Qaz. Chun. ItaL, 46 {1916), II, No. 2, pp. i22-i35).— Experimental data show 

 that by the action of carbon dioxid on an aqueous solution of calcium oxid or 

 on neutral calcium carbonate the bicarbonate, Ca(HC0s)2, is formed. 



The greatest quantity of calcium carbonate soluble (after prolonged 

 agitation of not less than 10 hours) in 1 liter of water at 0°, saturated with 

 carbon dioxid and maintained so at atmospheric pressure, was 1.56 gm., cor- 

 responding to 2.5272 gm. of the bicarbonate. Under analogous conditions at 

 15° C. 1 liter dissolved 1.1752 gm. calcium carbonate, equivalent to 1.9038 gm. 

 of the bicarbonate. 



By passing a rapid current of carbon dioxid through lime water saturated 

 at 15°, the first turbidity formed after about one minute soon clears, and then 

 a supersaturated solution of acid carbonate containing 2.29 gm. CaCOa, equiva- 

 lent to 3.71 gm. of the bicarbonate per liter, is formed. 



The determination of water in plant substances, A. N. Lkbediantsev and 

 G. I. Zalygin {Zhur. Opytn. Agron. {Jour. Agr. Expt.), 17 {1916), No. S, pp. 

 181-230). — In the determination of moisture in plant materials by heating to 

 100° O. in a current of air the authors observed a loss of carbon dioxid 

 and certain other volatile organic substances. A loss of material through 

 oxidation or hydration was thus indicated. Lowering the temperature of 

 heating (from 80 to 60°), diminishing the pressure, or replacing the air with 

 carbon dioxid did not perceptibly influence the loss of volatile matter other 

 than moisture. The most Important factor in the amount of loss was found 

 to be the time of heating. 



Drying in a desiccator with sulphuric acid or phosphorus pentoxid at normal 

 temperature also caused a loss, the amoimt depending on the duration of 

 the desiccation. An equilibrium, however, was reached in from four to seven 

 months, so that the actual loss could perhaps be considered negligible. 



The unreliability of the methods for the determination of moisture in plant 

 materials commonly used and the necessity of specifying some standards when 

 analytical data are submitted are indicated. 



A method for the quantitative determination of free and combined galac- 

 tose, A. W. VAN DER Haar {Cliem. Weekbl., 13 {1916), No. U, PP- 1204-1213, 

 fig. 1). — The following procedure for the determination of free galactose, which 

 depends on its oxidation to mucic acid with nitric acid, is described : 



A suitable sample (from 50 to 100 mg.) is treated in a beaker with 60 cc. of 

 nitric acid (specific gravity 1.15) and heated on the water bath with occasional 

 shaking until the material in the beaker weighs less than 20 gm. After cooling, 

 water Is added until the contents weigh exactly 20 gm. Five hundred mg. 

 pure mucic acid is added and the whole set aside for 48 hours at 15° C, 

 during which time the contents are occasionally agitated. The precipitated 



