AGMCULTURAL CHEMISTRY — AGROTECHNY. 507 



colostrum and old milk) it is better to conduct it with an alcoholic methylene 

 blue-formaldehyde solution. The reaction will not determine whether or not 

 the cow is in a new period of lactation. 



Are alkalinity and peroxidase synonymous? W. D. Koopeb (Ztschr. Unter- 

 such. Nahr. u. Genussmtl., 23 {1912), l^o. 1, pp. 1-13; abs. in Ztschr. Angew. 

 Cheni., 25 (1912), No. 17, p. So3). — The degi-ee of alkalinity, that is, the amount 

 of normal sulphuric acid required to discharge the violet color produced by 

 Rothenfusser's reagent for fresh milk, was 110.1 cc, and like the degree of the 

 acidity of milk it varies. In colostrum the degree of alkalinity is greater than 

 in normal milk, but the amount of sulphuric acid required falls as the period 

 of lactation goes on. In goat's milk the alkalinity degree is higher (120) than 

 in cow's milk. The author believes peroxidase and alkalinity synonymous. 



In regard to the guaiac test, K. Sciiebn and W. Schellhase (Berlin. 

 Tienirztl. Wchnscltr., 28 (1912), No. 13, pp. 221-223).— A discussion of Kiihn's 

 work (E. S. R., 26, p. 712), with some additional data in regard to the influence 

 of hydrogen peroxid on the test. It was found that when hydrogen peroxid is 

 added to the milk the guaiac reaction is Influenced considerably, but not when 

 the guaiac-guaiacol reagent is employed. Boiled sterile milk, without regard to 

 time, does not give a positive test with the guaiac-guaiacol reagent. 



Source of error in the determination of the Polenske number, W. Aenold 

 (Ztschr. Untersuch. Nahr. u. Gcnnssmtl, 23 (1912), No. S, pp. 3S9-39/).— Ac- 

 cording to the author, the difficulties encountered lie not with the method but 

 with the manipulator who neglects certain criterions laid dovsTi by the author, 

 and which it is absolutely necessary to follow in order to get correct results. 

 The method is described in detail. 



A new method for determining sugar, I. Bang (Lunds Univ. ArssJcr., n. 

 ser.. Sect. 2, 7 (1911), No. 8, pp. 1-10, pi. i).— The original Bang method is 

 open to the objections that the titration solutions are very expensive, the cop- 

 l)er solution is not stable, and an incorrect titration made with a copper solu- 

 tion can not be corrected. Attempts were made to displace the potassium 

 sulphocyanid with a cheaper salt, and potassium chlorid vms found to be a 

 good substitute, it also forming colorless compounds with cuprous oxid, but 

 had the disadvantage of being able to hold only small amounts of cuprous oxid 

 in the solution. It was also noted in this work that better results — end point 

 determination, etc. — could be obtained if the cuprous oxid was titrated directly 

 and not the unreduced cupric oxid, as in the older method, consequently iodin 

 1/iOO-normal was selected" instead of hydroxylamin. 



The other solutions necessary are as follows: (a) Potassium bicarbonate 160 

 gm., potassium carbonate 100 gm., and potassium chlorid 60 gm. are dissolved 

 in 700 cc. of watei*. The potassium bicarbonate is dissolved first, then the other 

 salts, followed by 100 cc. of a 4.4 per cent copper sulphate solution, are added, 

 and the solution filled to the 1,000 cc. mark with water. From this stock solu- 

 tion 300 cc. is diluted to the 1,000 cc. mark with a saturated solution of potas- 

 sium chlorid. The latter solution, which is stable, should only be employed 

 after standing for a few hours, (b) A solution of soluble starch, which con- 

 sists of 1 gm. of soluble starch in a saturated solution of potassium chlorid. 



The method is conducted as follows : Two cc. of the sugar solution, which is 

 only one-sixth as strong as the old method calls for, is placed in a 100 cc. Jena 

 flask, which has its upper rim removed, with 55 cc. of a copper solution. A 

 rubber tube about 5 cm. long is pulled over the neck of the flask until it stands 

 about two-thirds above the flask. The solution is boiled for 3 minutes, the tube 

 clamped with a pinchcock, and the boiling continued to the end of the 3-minnte 

 period. The flask is then removed quickly from the flame and cooled, the rub- 



65584°— No. 6—12 2 



