AGEICULTUEAL CHE3IISTEY — AGEOTECITSrY. 207 



and sewage <^T3ents !s c-onj?}dered in tbe first cliapter. but the bulk of the text 

 deals vritb the chemical ex&njjrxation of tcii-^'vealiiieoTis frx>d i^rod-QCts. .Selected 

 aiLal:.-tical inethcKis which h^ve been einjOJored bv the authors in their labora- 

 torr are Cer<rri!>e*L and iLfonn^&tion is given ret'ar'iirj^ the iiataral projierties of 

 food-s. the dete'-tion of jx/i.^jnouH metals, and preser-.fetive-; in foods. Qxapters 

 are also devotM to gas and urine aaaljHS. 



The determination of carbon by the wet method, F. BL Thies (Ch*yn.. Ztg^ 

 ZH (IfjiJi), Xo. 11, pp. Ho, 116, fy9. 2). — An un^orement of Ihe antiior's metbod 

 which allows the eRtiniatioa of halogen and nitrogen at the flame time with tte 

 carV^n. The products of oxidation obtained with potaaiimn diehromate sol- 

 phuric acid mixture are paaeeft orer heated lime to absotb the halogai and pait 

 of the carbcm dioxid and thrai through a wi^^bed soda lime tube to absorb the 

 remaining carbon dioxid. If lodln is presmt sOrer nitxate Is added to the 

 oxidation flask to retain the lodin as lalTa- iodid. In this ease hroain aad 

 clilorin are not retained. 



Triketohydrindene hydrate: A msthod tor the quantitative estsmaHon of 

 the IfH^COOH gTOop, E, Heszfeu) (Biochem. ZUchr^ 53 (19H). So. S-i, pp. 

 2^t-2//j). — The method eonsists of evaporating the sabstance under examina- 

 tion with tril&etofaydrindene iQ-drate or mnhjdrin (EL S. B., 26, p. 8(H| and 

 taking up the readne with akxibtA. The extinction ooeffidoit of the sc^ntion 

 is measored by the ^tectroiAotomf^er. The metboA has beoi app^ed to the 

 dlalyzate obtained in the Abderiialden method for diagjiosfns pregnancy (E. 8. 

 R., SU pp. 278, 279). 



The determination of invert sugar in the ijresence of saccharose, E. Sail- 

 LABD (Jour. Fafjric. Hucr., oo {l'^H>, Ho. •?, p. 1; a?»^. «n CAem, Ztg^ -58 (1514). 

 JTo. 4-7, Repert., p. 195). — ^In the presence of socroee, as Posbok has long ainee 

 shown, only solntions oontaining a small amoont of free alkali or none at all 

 flhonld be nsed in making the detmnination. It is daimed that Bertrand's 

 method does not jie!d reliable results in the presence of socrose. 



Modification of ClergeVs method for the e^lmation of sogar in molasses, 

 V. STAJfEK (ZUchr. Zuckerinduj-. Bohmen. .?8 (1-914), ^o. 9, pp. 429-WJ^ fi^- 1/ 

 abs. in .Jour. Cliem. Hoc. [London'^, 106 {19Hu 3"o. 621, II. pp. -585, -5*7 t. — In 

 the process described the molasses is deeoiorized. clarified with bromiiL and 

 polarized in the presoice of definite quantities of citric acid and potassium 

 chlorid. The bromin has no ^ect upon socrose and inrert sugar. 



Two citrate solutiwiB are employed and are prepared by mixing 380 gm. of 

 potassium hydroxid with 250 cc. of water. " When about three^oortfas of the 

 hydroxid has dissolred, the solution is decanted and 400 gm. of citric acid mixed 

 with 200 oc. of wato* added to it. The remaining hydroxid is then dissolved 

 in water and added to the citrate ttsAatiaa ontil the latter is feebly alkaline to 

 phenolphthal^n ; the solution is now oo<ded and dilated to 1 liter (neotral 

 citrate solution). Five hundred cc of this sedation is then mixed with 230 cc 

 of hydrochloric add {fs^exnStc gravity 1.1S9), and dilated to 1 liter (acid citrate 

 solution). A double-normal quantity of the molasses is dissolved in water and 

 diluted to 200 cc Fifty cc of this solotioa Is transferred to a KKKec llaeiE. 

 20 cc of the acid citrate solati<m is added, and the i^xlure is dilated to 100 oc 

 with saturated bromin wato'; after filtration, the solntioa Is polarized in a 

 2(^>mm. tube. .A. second qnantity of 50 oc of the molasHeis solation is now 

 treated with 10 cc of hydrochlone acid (1 : 1). inverted, cooled to 20°, 10 cc of 

 neutral citrate soltition is added, and the solution, is diluted to 100 cc with 

 bromin water. The reading is taken after the lapse of 20 minutes. An 

 inversifHMsmstant of 132.6 is employed in calculating the quantities of soerose 

 and invert sugar from the readings obtained at 20° ." 



5451'— Xo. 3—1" 2 



