6 EXPERIMENT STATION RECORD. 



bility of the carbon dioxid in the acid used in det-oniposing the carbonates. The 

 method proposed by the authors i* based upon the change in pressure produced 

 when the unknown volume of gas, i>roduced by tlie action in a partial or complete 

 vacuum of dilute sulphuric acid upon the substance containing the carbonate, expands 

 by a known volume which is measured by means of a glass bulb of known capacity 

 and a manometer connected with the generating bulb. The apparatus used is 

 described, the method of calculation of results is explained, and a number of deter- 

 minations by the method are rejiorted. 



On the estimation of alkaline hydrate or bicarbonate in the presence of 

 monocarbonate, B. North [Jouv. Sor. Cliem. Ltd., 21 {1902), No. 5, jyp. 322-325). 



The detection of magnesia in ammonium oxalate precipitates of lime, A. 

 Taubnee {Chem. ZUj., 26 {1902), No. 23, p. 246). — It is stated that magnesium oxa- 

 late is sufficiently soluble in water to give a precipitate of silver oxalate when silver 

 nitrate is added to the wash water of calcium oxalate precipitates. 



The determination of caesium and rubidium as hydrosulphate and of potas- 

 sium and sodium as pyrosulphate, P. E. Browning {Ztsdir. Anorgan. Chem., 29 

 {1901), No. 1, pp. 140-144). — Salts of ctesium and rubidium with volatile acids give 

 acid salts of the type IIHSO4 when treated with an excess of sulphurii- acid and heated 

 to constant weight at 250 to 270° C, and neutral salts of the type E^SO^when heated 

 to glowing. Under the same conditions potassium and sodium salts give pyrosul- 

 phates of the type R^^^a^),, which on heating are transformed into the neutral salts 

 R,SO,. 



A contribution to the knowledge of metaphosphate, A. AViesler {Ztschr. 

 Anorgan. CJtem., 2S {1901), No. 3, pp. 177-209, jiga. 3). 



On calcium carbophosphate, A. Barille {RcpeH. Pliarm., 1901, p. 145; ahs. in 

 Centbl. Agr. Chem., 31 {1902), No. 2, p. 136).— The author studied the solution of 

 calcium phosphate in a water solution of carbon dioxid under pressure. He found 

 that under these conditions a very unstable compound of biphosphate with carbon 

 dioxid was formed, to which he gives the formula P.^ O,^ H^ Ca^ 2CO2. By the action 

 of carbon dioxid on tricalcium phosphate there was formed first a biphosphate and 

 calcium bicarbonate. The presence of the latter reduced the soluliility of the biphos- 

 phates in water containing carbon dioxid to a very marked extent. Attempts to sep- 

 arate the calcium carbophosphate by cooling or adding alcohol failed, decomposition 

 and evolution of carbon dioxid taking place under this treatment. No reaction took 

 place when dry calcium biphiisi)liate was treated with dry carbon dioxid. 



Phospho-molybdenum compounds, F. Mawrow {Ztschr. Anorgan. Chem., 28 

 {1901), No. 2, i>p. 162-166; 29 {1901), No. 1, pp. 156-158). 



The use of weak solvents in soil analysis, A. D. Hall and F. J. Plymen 

 {Jour. Southeast. Agr. Col, Wye, 1902, No. 11, pp. 90-99, figs. 3). — Comparative tests 

 of citric, hydrochloric, acetic, and carbonic acids, and ammonium citrate as solvents 

 for available phosphoric acid and potash in Rothamsted soils of known history are 

 reported. The citric-acid method proposed by Dyer seemed to give results most in 

 accord with what was known of the soils. 



Report of the subcommittee on uniformity in analysis of materials for the 

 Portland cement industry {.Tour. Soc. Chem. Ind., 21 {1902), No. 1, jip. 12-30). 



The determination of nitrates in water by the indigo carmine method, S. R. 

 Tkotman and II. Peters {Jour. Soc. Clicjn. Ltd., 21 {1902), No. 10, pj>. 694, 695). — 

 The method proposed is as follows: "From 5 to 20 cc. of the water under examina- 

 tion is mixed with 25 cc. of indigo carmine solution. To this is added concentrated 

 sulphuric acid equal in amount to the united volumes of the water and indigo carmine 

 solution. The whole is then heated on the sand bath for 15 minutes. At the end of 

 this time, the excess of carmine solution is titrated with a standard solution of potas- 

 sium permanganate. In a similar manner, and alongside the above, a blank estima- 

 tion is done, replacing the water under observation by distilled water. The difference 



