19191 AGRICULTURAL CHEMISTRY — AGBOTECHJTT. 009 



Studies on the amylolytic activity of human saliva with a new method, 

 V. ( '. Mvkhs and A. (?. Pkllknbauqh (Proo. 8oc. Kxpt. Biol, and Med., 16 

 {1918), No. 2, pp. 18-20).— The technique of the method is as follows: 



A specimen of mixed saliva is filtered, and a small portion accurately diluted 

 (i:ioo) with distilled water and another portion with '».:; per cent ■odium 

 chlorid as an activating solution. After thorough mixing, l <•<•. of the diluted 

 saliva is pipetted into a test tube and the tube heated for five minutes in a 

 water hath at 40° C. One cc. of 1 per cent soluble starch solution is then 

 added, the mixture Incubated for 30 minutes, 3 cc. of saturated picric acid 

 solution and 1 cc. of 20 per cent sodium carbonate added, and the tube placed 

 in boiling water for from 15 to 20 minutes. After cooling the material is 

 diluted with distilled water in an accurately graduated cylinder until the in- 

 tensity of the color approximates that of the standard (glucose in picric acid 

 treated with sodium carbonate and heated), and is then compared with the 

 standard in the colorimeter. After correcting for the reducing power of the 

 BOluble starch, the activity is recorded in terms of the percentage of starch 

 converted into reducing sugar. 



With this method it has been found possible to obtain a demonstrable 

 amylolytic activity at a dilution of 1:400 when water was used as the diluent 

 and at a dilution of 1:2,000 with 3 per cent sodium chlorid. For purposes of 

 comparison, a dilution of 1:100 is thought to be the most suitable with dis- 

 tilled water as the diluent. 



For normal individuals the method has been found to give an activity be- 

 tween 30 and 4.1 when water was used as the diluent and between 46 and 50 

 with sodium chlorid. Figures obtained on the same individuals at the same 

 time of day agreed very closely. A considerable decline in activity of the saliva 

 was noted as a result of glandular fatigue produced by the continuous secretion 

 nf Baliva during parallin chewing. 



The preparation of sodium p-hydroxyphenylarsonate, J. B. Conant {Jour. 

 Amer. Ghem. 8oc, 41 (1919), No. 3, pp. 431-435). 



The classification of mimetic crystals, E. T. WHEBBT and E. Q. Adams 

 (Jour. Wash. Aruil. Sri.. <) {1919). No. 6. pp. 153-157). 



The permanent marking 1 of glass vessels, J. C. Bock (Jour. Amer. Chcm. 

 Soc, 41 (1919), No. 3, pp. 359-361). — The method described consists essentially 

 in fusing certain glass colors into the glass by means of an ordinary burner. 

 The color is mixed as thick as practicable with an oil composed of 4 parts of 

 copaiba balsam, 1 part clove oil, and 1 part lavender oil, and applied with an 

 ordinary steel pen or fine brush. The heatiug is applied carefully until the 

 markings glow. It is said that the marking thus obtained can not be removed 

 by mechanical or the usual chemical means. 



An all-glass nitrogen apparatus, E. R. Allen and B. S. Davisson (.bin, 

 Missouri But. Gard., 6 (1919), No. 1, pp. 45-48, pi- 1). — An all-glass nitrogen 

 apparatus devised particularly for use in nitrogen determinations in studies of 

 plant metabolism is described and Illustrated. The special features of the 

 apparatus are the elimination of rubber stoppers and connection, efficient scrub- 

 bing of the entrained alkali from the steam, and the use of I'yrex glass which 

 does not yield an appreciable amount of alkali to steam or boiling solutions. 



Arsenious oxid as a standard substance in iodimetry. It. If. OhAPIN (Jour. 

 Atncr. Chan. Soc, 41 (1919), No. 3, pp. 351-358).— The author at the Bureau 

 of Animal Industry of the U. S. Department of Agriculture reports an investiga- 

 tion to establish the reliability of properly purified arsenious oxid as a standard 

 to replace iodin in iodimetry. 



It was found that, by employing weight burets with appropriate precautions, 

 titrations against iodin of arsenious oxid prepared by the method previously 



