KEl'OKT OF CHEMICAL ]j.\BOK.\TOKY 



231 



SENEGAL GUM. Csude 



GOMME DU BAS DU FLEUVE 



GALAM 



H. R. & Co. 



H. R. Sl Co. 



Soc. I. et T. 



Collected in com- Collected higher up 



paratively moist the river unde; 



atmosphere near more normal 



the sea conditions 



II. R. iS: Co. 



Soc. I. et T. 



SALABREDA 



Soc. I. et T. 



It -would appear that the Kordofan gum is more uuifurm in rumpusitiou, and tliat 

 the Senegal crude gums contain a notable proportion of weaker gums, possibly from 

 varieties other than ^1. Seneyal. 



Both hard and soft Kordofau gums are obtained from the A. Verek (Hashab). The 

 hard variety is collected as noted above from young, and the softer from older trees. At 

 the present time the two are collected together ; but abroad they are picked out, the 

 hard variety, it is said, for dyeing and finishing silks and other fabrics, and the softer 

 for confectionery and fine pharmaceutical products, etc. 



Notes on the Determination of Viscosity of Gum Solutions 



Several samples of Sudan gum tested at the Imperial Institute were subsequently Determination 

 examined in this laboratory. The comparative viscosities obtained were so much at variance ° "^'^"^"y 

 that a number of experiments were instituted iu order to determine the conditions affecting 

 this determination and the possible sources of error. 



The instrument employed at the Imperial Institute might be described as a minute 

 pipette, the bulb of which had a capacity of about one half a c.c, and the outlet being a capillary 

 tube ten centimetres long. The determination was made by filling the bulb with the liquid to be 

 tested and noting the number of seconils required to discharge through the capillary tube. 

 This averaged something like ten seconds. 



There are several objections to such a form of instrument, among which maj' especially 

 be mentioned the want of provision for controlling the temperature, the shortness of the time 

 of observation, and the tact that it will not permit of observation on any but comparatively 



