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SCIENCE 



[Vol. LVI, No. 1460 



1.0 mg. is about the limit for the sulfide method. 

 "(2) The test ^ould be carried out in a solutdon 

 aboTit one half normal Triith acetic acid and should 

 contain ammonium salts. Warming to 60 aids 

 flocculation. (3) The ferrocyanides 'of the alka- 

 line earth metals are too soluble to interfere, 

 other metal ions must be removed. (4) The yellow 

 color mth broonine water is also given by cad- 

 mium ferrocyanide. 



Qualitative analysis without hydrogen siUfide 

 E. D. MuLLiNix. G. Almkvist has proposed a 

 method without the use of H2S, but NaoS fol- 

 lowed by H2SO4. (Zeit. anor. Chem., 103, 221 

 242, 1918). I have used for the past two years 

 with qualitative classes a method dn which, after 

 the removal of the silver group by HCl, a mix 

 ture of NaOH, Na2003 and bromine water pre^ 

 cipitates a group of hydroxides and carbonates 

 which are then further separated. The As, Sb 

 Sn, Pb traces, An, Al and Cr are in the filtrate. 

 This is divided by HCl followed by NH4OH, and 

 zinc tested for in the presence of chromate and 

 arsenate by the poibaissium ferrocyanide method. 

 This is a preliminary communication and will be 

 followed by more detailed work on the group 

 analyses and end tests. 



DrVISION OF SUGAR CHEMISTBY 



S. J. Osborn, chairman 

 Frederick Bates, secretary 

 Detection of sugar in condensed waters hy 

 means of oresol: G. E. Stevens. Fifteen ml. of 

 cresol (U. 8. P. Merck) is disisolved in a castile 

 soap solution (6 gms. soap in 100 c.e. of distilled 

 water). The mixture is warmed until a complete 

 solution is obtained. This solution can be made 

 up in litre quantities in the albove proportions 

 without deterioration. Approximately one inch 

 of water to be examined is placed in a 6 inch hy 

 % inch test tube and five to ten drops of the 

 cresol solution is added and then thoroughly 

 mixed. Cool if the water is hot and then add 

 concentrated sulfuric acid from a dispensing 

 burette, holding the tube in an inclined position 

 so that the acid will run down to the bottom and 

 form a separate layer, and continue to add the 

 acid until the acid layer is % inch deep. The 

 tube is then rolled between the palms of the 

 hands and if sugar is present a reddish black to 

 pink color ring will develop, the color depending 

 upon the concentration of sugar in solution. A 

 white translucent screen is recommended, to be 

 placed between the eye and the source of light, 

 such that the color reaction irill be more easily 



recognized, especially in solutions containing very 

 faint traces of sugar. 



Sydrogen-ion determination as a method of 

 refinery control. Preliminary report: H. Z. E. 

 PerkIiSTS. Direct control of acidity and alka- 

 linity in sugar refining is obtained only, at cer- 

 tain points, chiefly at beginniag. After washing, 

 sugar goes through main process of clarification, 

 bone-black deeolorization and crystallization with- 

 out material change in ionization. By-products 

 are unstable in composition, ferment quickly and 

 are moreover treated with defecating agents, acid 

 and alkaline. Ionization is variable, being re- 

 sultant of several factors, natural and artificial. 

 Main products, highly crystalUzable, light in 

 color, are easily tested with color indicators, but 

 appear sluggish and uncertain with potentiometer. 

 Lower products, dark colored, can not be used in 

 color reactions, but respond better to electro- 

 metric tests. Figures are given showing varia- 

 tions and stability. 



A study of the formation of gum levan from 

 sucrose: W. L. Owen. The formation of gum 

 levan from sucrose by bacteria is not, as has 

 been claimed by previous investigators, dependent 

 upon its inversion and the utilization of invert 

 sugar while in the nascent condition. Experi- 

 ments on the production of gum levan in the 

 presence of added invertase show that under these 

 conditions it is decreased to the extent to which 

 the invertase is active. The decrease is always 

 greatest where the conditions are most favoralble 

 for invertase action. The optimum p^^ for gum 

 production is between 6.7 and 7.0, but the fer- 

 mentation can proceed slowly where the Pj^ is 9.5. 

 Under the latter conditions the addition of inver- 

 tase does not reduce the production of levan by 

 the bacteria. 



The invertase value of the clerget constant: 

 E. F. Jackson. 



A simple checTc valve: J. F. Brewster. A 

 check valve for use with the water vacuum pump 

 to prevent sucking back is made by cutting part 

 way through a solid rubber stopper at the narrow 

 end, leaving a thin fiap or disk. The stopper is 

 then bored to receive a piece of glass tubing, 

 the fiap being left rataet. The valve stopper is 

 inserted in a short length of glass tubing wide 

 enough to allow free play of the valve. By means 

 of a second one-hole stopper, glass and rubber 

 tubing the valve is connected between the pump 

 and the apparatus to be evacuated. 



Some notes on activated vegetable chars: C. E. 

 CoATES. This article gives some data relative to 

 the preparation and analysis of vegetable chars 



