lf>l»] AGRICULTURAL CHEMISTRY — AOROTECHNY. 20.3 



(Jour. Amcr. Chem. Soc, 40 (1918), No. 12, pp. 1940-194/,).— This article is one 

 of a series of quantitative studies of the various chemical and physical factors 

 governing the growth of fungi on culture media and trees, made at the New 



York State College of Forestry at Syracuse University in ( Deration with 



the Bureau of Plant Industry, U. S. Department of Agriculture. 



The Indicators reported upon in this paper are phenolsulfophthalein and the 

 tetrabromo and tetranitro derivatives. The general plan of study was to find 

 the wave-lengths at which the indicator solutions give a transmission of 20, 

 40, 60, SO, etc., per cent and to calculate the corresponding absorption indexes. 

 From the results obtained the following conclusions are drawn : 



"These sulfophthaleins are twice as deeply colored as phonolphthalein in 

 alkalis and show sharper color changes. The excess of alkali necessary to 

 produce- the end-point of the neutralization of the Indicator does not cause any 

 appreciable fading in either short- or long-time periods in the case <>f phenol- 

 sulfophthalein and its tetrabromo derivative. The color of phenolsulfophthaleln 

 in phosphate buffer solutions does not fade appreciably, even in considerable 

 time periods. Standardized stock solutions of phenolsulfophthalein can be kept in 

 an Ice box without appreciable change, or even at ordinary temperatures if care 

 is given to prevent contamination, and will then show the same absorption index 

 when treated with an excess of alkali at different time periods. Different sam- 

 ples of the same lot of solid well-mixed phenolsulfophthalein will give the same 

 absorption index when treated with an excess of alkali. An excess of alkali 

 in solutions of tetranitrophenolsulfophthalein causes a fading of the intense red 

 color to a light yellow, the time of fading depending upon the amount of alkali 

 and other experimental conditions." 



A modified method for the preparation of picramic acid, G. Egerer (Jour. 

 Biol, Chem., 35 (1918), No. 8, pp. 565, 566).— A modified method of preparing 

 picramic acid is described which is said to yield 76.5 per cent of the theoretical 

 value. The usual method of neutralizing a cold saturated alcholic solution of 

 picric acid with ammonium hydroxid and then saturating the solution with 

 hydrogen sulphid is modified by using an excess of ammonium hydroxid to 

 prevent the crystallization of unchanged picric acid and by cooling the mix- 

 ture during saturation with hydrogen sulphid to prevent the formation of the 

 ammonium salt of the diamino acid. 



On the extraction of ammonia from soil, T. E. Richmond (Foil Sri.. 5 

 (1918), No. 6. pp. 481-486). — This is a report of a study conducted at the Ohio 

 Experiment Station of the relative amounts of ammonia extracted from soils 

 by water and by 5 per cent hydrochloric acid. 



The soils used were all surface soils, air dried, and ground sufficiently fine 

 to pass through a 2-mm. sieve. Three types of soil were used — an acid silt 

 loam deficient in bases and organic matter, a basic black clay rich in organic 

 matter, and a very acid peat soil. Portions of the soils were placed in 1-liter 

 bottles, and ammonium sulphate sufficient to supply 0.1484 gm. of nitrogen was 

 added to half the bottles. Water or 5 per cent hydrochloric acid was added 

 at the rate of 500 cc. per 100 gm. of soil and the extraction continued for 30 

 minutes with constant shaking in a machine. Nitrogen as ammonia was de- 

 termined by distilling duplicate 200-cc. portions with 0.5 gm. of freshly cal- 

 cined magnesium oxid, first neutralizing the acid extracts with sodium hy- 

 droxid. Further data were obtained by the use of soils treated with casein, 

 sulphur, and calcium carbonate. 



The results show that, while in no case did the water extraction give the 

 full amount of ammonia from different soils, in each group a certain ratio 

 appeared to exist between the amounts extracted by the two methods. From 



