AGRICULTURAL CHEMISTRY AGROTECHNY. 415 



excess. Tliis additioual amount of iodiu determines the amount of tliiosul]»liate 



sulphur. For a 25 cc. sample the Ki'Jims per 100 cc. of original st)lulion is 



Cc. iodin X 0.0064 X 1000 

 given by the computation 25 '' 



" Sulphate and sulphite sulphur are determined together by precipitation in 

 the cold as barium sulphate after filtering off the sulphur from the solution 

 used for the monosulphid and thiosulphate sulphur determinations. 



" Total sulphid sulphur may be determined by dissolving the sulphur pre- 

 cipitate, filtered off for the snli)hate sulphur determination, in concentrated 

 potassium liydroxid, oxidizing and precipitating as barium sulphate. 



"The calcium oxid may be determined by oxidizing the sulphur to the sul- 

 phate form and precipitating the calcium as the oxalate. It may also be 

 determined by computation from the amount of iodin used in the monosulphid 

 and thiosulphate sulphur determinations and from the amount of sulphate and 

 sulphite sulphur present. The following computation gives the number of 

 grams per 100 cc. : (Cc. iodin used for monosulphid sulphur) + (2 X Cc. iodin 



002s X 1000 

 used for thiosulphate sulphur) X -^ 05 ^ (sulphate and sulphite 



sulphur) X 1.75." 



In regard to the advantages of these methods over old methods, it is noted 

 that the use of sodium peroxid as an oxidizing agent is more convenient than 

 either hydrogen peroxid or bromin water. Furthermore, substituting iodin 

 titration for ammoniacal zinc chlorid ^lution does away with the filtering off of 

 test portions for determining the end point by an external indicator. The dis- 

 solving of the zinc polysulphid sulphur or sulphur precipitate and the treatment 

 of the solution with acid as a preliminary to making the thiosulphate sulphur 

 determination are eliminated, and a "method of determining the calcium oxid 

 present by computation from the decinormal i(xlin used for the thiosul])hate and 

 mon(»snlpliid sulpliur determinations and from the sulphate and sulphite 

 present" is introduced. 



About a sensitive glue reaction, E. Schmidt (Chctn. Ztg., SJ/ {1010), No. 9//, 

 p. 839; abs. in Zcnthl. Bmchcm. u. Biophys., 10 {1910), No. 17-18, p. 1179).— It 

 to a glue solution there Is added, in the cold, an aqueous solution of ammonium 

 molybdate (3 gm. to 250 cc. of water) and a few drops of dilute nitric acid, a 

 white precipitate is produced which settles very quickly and after a short time 

 assumes a blue-green color. The supernatant liquid also assumes this color. 

 The precipitate dissolves on heating and only a slight turbidity remains. 



Report of the activities of the agricultural experiment station at Hilde- 

 sheim, Aumann {Ber. Lnndw. Vers. Stat. Hildesheim, 1910, pp. Iff). — This is 

 a report on the activities of the station from November 1, 1909, to October 31, 

 1910, and deals with results of analyses of artificial fertilizers (8,011 samples, 

 of which 3,802 were Thomas slag powder) ; commercial feeding stuffs (8,097 

 samples) ; soils (179 samples) ; various commodities of the sugar industry and 

 other technical substances and foodstuff's (2,445 samples, of which 1,184 samples 

 were waters) ; and 220 samples of seeds. 



Drying' machinery and practice, T. G. Maulow {New York and London, 

 1910, pp. XX-\-32G, pis. 17, figs. 17.)). — This is a handbook on the theory and 

 practice of desiccating and drying, and contains a classified description of the 

 installations, machinery, and other apparatus. The topics treated in the work 

 which are of interest to agrotechny are the desiccation of albumin, ashes, 

 asphalt, barley, beet and cane sugar, blood, bone meal, bran, brewery grains, 

 cement, cocoa, distillery draff, excretions, feathers, fiber, farina, flax, flour, 

 fruits, grain, hops, oats, leather, marl, manure, meat, molasses, phosphates, rice, 

 rubber, spirits, superphosphates, and wood. 



