AGRICULTURAL. CHEMISTRY — AGROTECHNY. 9 



cau easily be constructed iu the laboratory, for preparing as luuch as 5 liters 

 of ammonium citrate sokition at one time is described. 



A critical study of methods for determining the hardness of natural 

 ■waters, J. M. Silbeb (.Irc/i. Hyg., 73 (1911), No. 2, pp. i7i-i82).— Wartha's 

 method^ for determining the transitory hardness, when modified according to 

 the author's specifications, yields good results, but otherwise leads to error. 



In regard to the determination of proteins and the digestion of protein 

 by pepsin, F. Westhaussek {lloppc-Srylrr's Zfschr. Physiol. Chem., 12 {1911), 

 No. 5-6, pp. 363-373; ahs. in Zentbl. Physiol., 25 (1911), No. 16, p. 673).— De- 

 terminations of proteins by Stutzer's method and by precipitation with tannin 

 generally yield the same result. The methods can also be used for separating 

 protein from amid nitrogen. On the other hand, varying results were obtained 

 when the methods were used for separating the cleavage products resulting 

 from the action of pepsin on protein. Identical results were obtained in fecal 

 analyses. 



The measurement of the oxidase content of plant juices, H. H. Bunzel 

 (U. S. Dept. Agr., Bur. Plant Indus. Bui. 23S, pp. JfO, pis. 2, figs. 9; Jour. Amer: 

 Chem. Soc, SJf (1912), No. 3, pp. 303-316, figs. 2). — Inasmuch as practically all 

 of the tests heretofore reported for studying the activity of plant oxidases are 

 of a more or less qualitative nature, a new method is described in which the 

 oxygen is absorbed by pyrogallol through the agency of the plant juice, and the 

 carbon dioxid developed is determined with sodium hydroxid. The oxygen 

 absorbed is noted by means of the manometer. 



The apparatus employed in the method is as follows: (a) A compact oxidase 

 apparatus constructed entirely of glass, and with which it is possible to con- 

 duct the entire reaction, that is, oxygen and carbon dioxid absorption in the 

 same apparatus (the apparatus also has connected with it a graduated apparatus 

 for adding the reagents and the plant juice without discoamecting in any way) ; 

 (b) a compact titration apparatus for determining the amount of carbon dioxid 

 absorbe<I by the sodium hydrate solution; and (c) an electrically heated and 

 controlled thermostat for conducting the oxidase reactions under uniform tem- 

 peratures and conditions. The thermostat also contains a shaking device. 



Some tests with the apparatus and potato peelings for furnishing the oxidase 

 preparation, and some with normal beet leaves and others affected with curly 

 top disease, are recorded, and which show that the apparatus furnishes con- 

 cordant results. 



On the determination of dry matter in roots, H. Goldschmidt (Alcelkeritid., 

 25 (1912), Nos. 1, pp. 12-15; 2, pp. 33-38; 3, pp. 63-10, figs. 4)-— A new method 

 of determining the dry matter content of roots is described, and the apparatus 

 used is illustrated. Samples weighing about I kg. are ground and dried in a 

 specially constructed drying apparatus at steam heat for a period of from 

 48 to 72 hours, according to the number of samples being dried. Comparative 

 results obtained with samples of different sizes are reported, showing a gen- 

 eral agreement to within a few hundredths of 1 per cent. 



A study of the carbohydrates in the prickly pear and its fruits, R. F. 

 Hare (New Mexico Sta. Bui. SO, pp. 30). — This is a continuation of previous 

 work (E. S. R., 19, p. 65). Among other objects, this investigation was to 

 determine the composition of the mucilage, which this plant contains during its 

 cycle of growth but which disappears at the ripening period, with a view of 

 ascertaining its function and its possible economic uses. 



"The juice of the ripe fruit contains 1.57 per cent of pentosans and only 

 traces of galactan. When previously precipitated with lead acetate, the juice 



iZtschr. Angew. Chem., 15 (1902), No. 9, p. 198. 



