AGRICULTURAL CHEMISTRY — AGROTECHNY. 511 



Tobacco extracts and their value, J. Schroder (Ztschr, Analyi. Chem., 

 50 {1911), No. 7, pp. 433-Ji35; abs. in Analyst, 36 {1911), No. ^25, pp. hi I, 

 412). — The author believes that the best method for payiug for tobacco extracts 

 is on the basis of the nicotin content. The luetliod employed for determining 

 the nicotin is as follows : 



"The extract (10 gm.) is mixed with so much dry sand that a dry powder 

 results. This is slightly moistened witli alcoholic potash, placed in a thimble, 

 and extracted with ether for 5 hours. The extract is cautiously evaporated to 

 two-thirds its bulk on tlie water batli. To the residue 200 cc. of 1 per cent 

 aqueous caustic soda are added, and the mixture distilled in a current of steam 

 until the distillate amounts to 500 cc, the residue in the flask at the end of the 

 operation being 60 to SO cc. The nicotin in the distillate is then estimated by 

 titration witli tenth-normal sulpburic acid." 



The detection of nitrates and nitrites in water, G. DenigI;s {Bui. 8oc. 

 Chim. France, 4. ser., 9 {1911), No. 11, pp. 5U-5'i6; ahs. in Analyst, 36 {1911), 

 No. .'/25, p. .'i32). — The reagent (hydrostrychnin) used for detecting nitrites and 

 nitrates in water is prepared by mixing together 5 cc. of a 1 per cent aqueous 

 solution of strychnin, 5 cc. of hydrochloric acid (specific gravity 1.18 to 1.19), 

 and from 4 to 5 gm. of pure granulated zinc, heating tlie mixture to the boiling 

 point, leaving it for from 5 to 10 minutes at the ordinary temperature, cooling 

 it in water, and decanting the supernatant liquid. If 0.5 cc. of this reagent 

 is added to 10 cc. of water containing nitrites, a rose-red coloration is imme- 

 diately produced. When the amount of nitrous acid does not exceed 0.1 mg., 

 a colorimetric estimation of the amount present may be made by comparison 

 with standard solutions of nitrites. 



Nitrates can be detected only when a few drops of sulphuric acid are added 

 to the water. When nitrates are to be determined the nitrites may be removed 

 by evaporating 10 cc. of the water to dryness with from 3 to 4 drops of acetic 

 acid and 2 drops of ammonia. The residue from this is taken up with 10 cc. 

 of distilled water and tested as usual. Chlorids do not interfere with the 

 reaction. 



Determination of sulphur, G. Anelli {Oaz. Chim. It ah, Jfl {1911), I, No. 

 2-3, pp. 334-341 ; ahs. in Jour. Soc. Chem. Indus., 30 {1911), No. 9, p. 573).— 

 The Carius method invariably gave high results with pure sulphur. This was 

 found to be due to the action on tlie glass of the sulphuric acid produced. The 

 silica thus libei-ated is weighed as barium sulphate. 



The author believes that accurate results can be obtained if the sulphur or 

 sample containing it is heated with a mixture of nitric acid and barium nitrate. 



The technic of precipitating with phosphotungstic acid, E. Wechsler 

 {Hoppe-Seyler's Ztschr. Physiol. Chem., 73 {1911), No. 1-2, pp. 138-143).— This 

 work was done with albumoses (proto- and deutero-), arginin, histidin, lysin, 

 guanidin, methyl guanidin, creatinin, phenylalanin, guanin, and adenin for the 

 purpose of determining the behavior of the different phosphotungstic acid pre- 

 cipitates obtained wth them in acetone solution. From the results it is con- 

 cluded that the acetone method is a good one for working up phosphotungstic 

 acid precipitates. 



Determination of chlorids, chlorates, and perchlorates in mixtures of the 

 same, Makqueyrol {Ann. Chim. Analyt., 16 {1911), No. 5, pp. 167, 168; abs. in 

 Jour. Soc. Chem. Indus., 30 {1911), No. 11, p. 682). — The method proposed is 

 based on the principle that hot nitric acid will completely decompose chlorids 

 and chlorates and convert tliem into nitrates while perchlorates are stable. 



A new form of extraction apparatus, C. K. Francis {Jour. Indus, and 

 Engin. Chem., 3 {1911), No. 9, pp. 673, 674, fiQS. 5).— The apparatus consists of 



