550 EXPERIMENT STATION RECORD. 



Chemical analysis of soils, K. ('orradi ( llol. ('him. Farm., 4~{i''0.3), P]>- 482-/^6; 

 nliK. ill i'hcin. Cciitlil., 1903, If, .\<k / /, />. .svr,).—\\i coiitiimation of a i)revii)us article 

 (K. S.R., 14, p. SS4) tho author tk-scrihc's luethocls of determining chlorin and manga- 

 nese and explains a correction for the presence of coarse particles. Some results of 

 examination of samples of Sicilian soils rich in lime and poor in nitrogen are 

 rejKH-ted, and the general sul)ject of fertilizer recjuirements of soils is discussed. 



Contribution to the knowledge of the molybdo-phosphoric acid reaction, 

 C. Rek iiAin) (Clii'iii. Zti/.. ,.-'7 (1903), No. 6S, pp. SSS-So'>). — This is an account of a 

 stihly of this reaction under varying conditions of proportion of reagents and presence 

 of certain acids (hydrochloric, tartaric, citric, and oxalic). The results obtained 

 indicate that the molybdic reagent used in amounts furnishing as much as .'iO parts 

 of M0O3 to one part of P^Oj, in case of solutions containing as little as 0.000186 gm. of 

 phosphoric acid per cubic centimeter after several hours' standing, gives no trace 

 of a precipitate. In the majority of cases to insure the precipitation of one part of 

 P^Og, it is necessary to add 200 parts of ammonium molybdate, and that the solution 

 of molybdate should be of at least 4 per cent strength. 



The presence of hydrochloric acid was found to seriously interfere with the forma- 

 tion of the yellow precipitate, but this was (\vercome by neutralization, preferably 

 with ammonia. Dilute solutions gf the acid interfered more with precipitation than 

 stronger solutions. The organic acids were variable in their behavior toward the 

 reaction, but in all cases interfered with precipitation. Oxalic acid was especially 

 marked in its preventive action. Neutralization of the organic acids in a measure 

 prevented interference with precipitation, and it appeared to be immaterial whether 

 ammonia or the other alkalis were used for this purpose. 



A method for the estimation of chlorids, bromids, and iodids, 8. Bexedict 

 and J. F. Sxell {.Tour. Atner. Clteni. Soc, S5 {1903), Xo. 11, pp. 113S-1U1).— In con- 

 tinuation of a previous article (E. S. R., 14, p. 225) the authors outline the following 

 method for the determination, either gravimetrically or volumetrically, of the 3 

 halogens : 



"For the determination of the iodin, a suitable quantity of the substance (contain- 

 ing not over 0.5 gm. iodin or 0.15 gm. chlorin, if tenth-normal solutions are to be 

 used) is dissolved in water and made up to about 50 cc. in a 100 cc. glass cylinder 

 with close-fitting glass stopper. Neutral potassium iodate is added in about twice the 

 quantity necessary to react with all the bromin and iodin believed to be present. 

 The mixed solution is acidified with 4 or 5 ec. fifth-normal (30 per cent) acetic acid 

 and shaken with 30 to 40 cc. carbon bisulphid until all the lil)erated iodin has been 

 taken up by the latter. The aqueous phase is now separated from the carbon bisul- 

 phid j)hase by filtration through a wet filter, and the carbon bisulphid is thoroughly 

 washed with cold water on the filter. The filtrate and washings are reserved for the 

 chlorin determination. The carbon bisulphid solution is transferred to another 

 beaker by puncturing the filter and is covered with 20 to 25 cc. of 75 per cent alcohol. 

 Any carbon ])isulphid left adhering to the filter is rinsed down into the beaker with 

 a portion of the 75 per cent alcohol. The iodin is now titrated with sodium thiosul- 

 phate with constant stirring. No starch indicator is necessary. 



"For the determination of the chlorin, the aqueous filtrate from the carbon bisul- 

 phid is treated with 5 cc. fifth-normal nitric acid (sp. gr. 1.18) to lil)erate the bromin 

 and is boiled in a covered beaker until colorless. The excess of iodate is next 

 destroyed by adding a quantity of i^otassium iodid slightly in excess of the amount 

 necessary to react with it. The solution is again boiled until colorless, 2 or 3 cc. more 

 of the dilute nitric acid being added, if the color is not completely discharged after 10 

 or 15 minutes' boiling. A minute or two after the color has completely disappeared 

 the solution is taken from the flame, cooled, and neutralized with sodium carbonate. 

 To secure exact neutralization, a little calcium carbonate may be added at first and 



