20 EXPERIMENT STATION RECORD. 



The distribution of nitrogen in a Cheddar cheese 6 months old was 

 found b)' this method of analysis as follows: Insoluble portion 3.18, 

 an)umoses 0.06, peptones by tannin O.K!, peptones by phosphotung-- 

 stic acid 0.13, amids 0.86, and ammonia 0.01) per cent. 



The following notes are given on the Kjeldahl method as applied to 

 milk and cheese: 



"(1) In determining the total nitrogen in milk or cheese it is necessary to boil with 

 sulphuric acid a considerable time after the solution is clear, as it will otherwise 

 froth badly when distilling. With 2 gm. of cheese 3 hours' digestion is none too 

 long. 



"(2) In digesting the filtrates from milk in the methods described in this article, 

 they must be watched closely, or they will froth badly when the water has nearly 

 boiled off, and the flame must be turned very low for from a quarter to half an h(jur. 



"(3) The filtrate from zinc sulphate bumi^s during dige.stion with sulphuric acid 

 until the water has been driven off. About half a gram of zinc dust added as the 

 flasks are placed over the flame will prevent it. 



"(4) In the opinion of the writer, the use of potassium permanganate and potas- 

 sium sulphid is unnecessary in nitrogen determinations m milk and cheese, and 

 their use has for some time been abandoned. . . . 



"(5) [The use of potassium sulphate and mercury for digestion as recommended 

 by Atterberg (E. S. R., 10, p. 605) was tested.] The writer made 50 determinations 

 in which 10 gm. of potassium sulphate and 0.7 gm. of mercury were used in one of 

 the duplicate samples, and the plain Kjeldahl, or Gunning, method in the other. 

 In every case the employment of both reagents shortened the time of digestion from 

 20 minutes to Ih hours, according to the substance used." 



Chemists' guide for the examination of foods, condiments, commercial 

 products, etc., F. Elsnek (Die Praxii^ des Clu'iidkers bei Vnti'miicliuiuj con Xdhrungs- 

 mitteln, Gmussmitteln and Gebrauchxyegenstdndeii, etc. Hainburg and Leipsic: Leopold 

 Voi<s, 1900, fgK. 182). 



Phosphotung-stic acid as a reag'ent for potash, E. Worker {Ber. Deut. Farm. 

 GeaelL, 10 {1899), pp. 4-0; nbs. in Chem. Centbl., 1900, I, No. 9, p. 517). — The use of 

 a 10 per cent solution of commercial crystallized phosphotungstic acid is recom- 

 mended for the detection of small amounts of potash. In neutral or acid solutions 

 of potash salts this reagent produces a white precipitate. 



Substitutes for hydrochloric acid in testing carbonates, J. W. Rich.\rds and 

 N. 8. PowELi. {.Tour. Aiuer. Clteut. Soc, 2 J {1900), No. ■), pp. 117-121). — Acid potas- 

 sium sulphate, oxalic acid, citric acid, and tartaric acid were tried as substitutes for 

 hydrochloric acid in ])roducing effervescence with natural carl)onates in the field. 

 Tartaric acid was found to be the best of the reagents tried, and citric acid nearly as 

 good, both giving satisfactory results. 



The volumetric determination of magnesia, J. 0. Handy {Jour. Amer. Chem. 

 Soc, 22 {1900), No. 1, pp. 31-39). 



On the determination of carbon and hydrogen by combustion in oxygen, 

 using copper oxid, C. F. M.\behy and W. R. Clymek {.Jour. Amer. CJiem. Hoc, 22 

 {1900), No. 4, PP- 213-218). 



On the determination of ammonia and nitrogen, A. Villiers and E. Du.mes- 

 NH. {Vinitpt. Rend. Arad. Scl. P(trh, 130 {1900), No. 9, pp. 573-576; Bui. Soc. CIrhn. 

 Parh, 3. scr., 23 {1900), No. 7, pp. 253-256; abs. in Chem. Centbl. , 1900, I, No. 13, p. 

 733). — The organic nitrogen is converted into ammonia and the ammonia expelled 

 by boiling with alkali as in the Kjeldahl method. Instead of titrating to determine 

 nitrogen, h(jwever, the acid solution is evaporated to dryness and the ammonium 

 chlorid weighed. 



