AGRICULTURAL CHEMISTRY — AGROTECHNY. 205 



under actual working conditions, was 93 per cent, and the recovered molybdic 

 acid obtained by evaporation and roasting at 600° tested chemically pure in all 

 cases. 



The cost of recovery is practically nothing. 



The effect of ammonium chlorid upon ferric and aluminum hydroxids dur- 

 ing- ignition, H. W. Daudt {Jour. Indus, and Engin. Chcni., 7 {1915), No. 10, 

 pp. S^7. 8-'f8). — Experimental work cited indicates that the washing of ferric and 

 aluminum hydroxids free from ammonium chlorid is unnecessary. No loss oc- 

 curred in either hydroxid by washing with ammonium-chlorid solutions of con- 

 centrations of 1 per cent or lower, and it was found to be advantageous to have 

 small quantities of ammonium chlorid present in the wash waters on account 

 of the tendency of the precipitate to become colloidal when electrolytes are alto- 

 gether absent. By precipitating the aluminum hydroxid in hot solution, boiling 

 the suspended precipitate for approximately 4.5 seconds and transferring to 

 the filter immediately, no difficulty was experienced in getting easy and rapid 

 filtration. 



Determination of dextrin and sugars in food products, C. F. Muttelet 

 {Ann. Falsif., 7 {19U), No. 69, pp. 372^80).— Continuing the work previously 

 noted (E. S. R., 31, p. IS), a procedure is given which includes also the de- 

 termination of dextrin. 



In the method 20 gm. of the preserve is transferred with the aid of tepid 

 water to a 200 cc. flask, then lead subacetate is added for the purpose of defeca- 

 tion, care being taken to avoid an excess (should an excess be used it may be 

 removed with bicarbonate of soda). Water is added to make the volume to 

 200 cc, and the solution is decolorized with animal charcoal. The reducing 

 sugar is determined in the solution so obtained and the results {p) are cal- 

 culated as invert sugar to 100 cc. of solution. The amount of reducing sugar 

 present after inversion ((7=sugar in 100 cc. of solution after inversion) is then 

 found. This is followed by determining the sugar after inversion with hydro- 

 chloric acid for 20 minutes in the autoclave at 110° C. This is calculated as 

 grams of sugar in 100 cc. of solution and is represented by m. The rotation of 

 the original solution is established at 20° in the 200 mm, tube and expressed 

 as D. 



The amount of sucrose {S) present in the solution is found as follows: 



S=[0.95 {q—p)], and corresponds to a rotation (e) of (1.33°-S). 



The quantity of dextrin A— [0.90 {m—q)] corresponds to a rotation of 5= 

 8.9 A degrees. 



The sum of the weight of glucose (G) and levulose (L) corresponds to a rota- 

 tion of d. 



d=D — {c-{-d) from which is obtained L and G. 



L=il()QXp)—d 

 2.93 



G={p—L) gm. 



The results of some trials with fruits, jelly, marmalade, comfits, and sirups 

 with the method are given. 



Note on the determination of sulphates in bread, C. D. Howaed {Jour. 

 Indus, and Engin. Chcm., 7 {1915), No. 9, p. 807). — ^After reviewing former 

 methods for the determination of sulphates in flour and bread, the author states 

 that he has adopted the following procedure : 



" Twenty-five gm. of the air-dry ground bread was digested for two to four 



hours on the top of the water bath at gentle heat with 200 cc. of 5 per cent 



hydrochloric acid, the mixture being well stirred at intervals. After cooling, 



the clear extract was decanted through a folded filter, the residue washed two 



22434°— No. 3—16 2 



