104 C. U. C. P. ALUMNI JOURNAL June, 1918 



Substitutes for Platinum Ware 

 R. F. Heath, in Met. and Chem. Eng., 19 17, 17, reports on test made with 

 a view of determining whether or not any substitutes for platinum ware were 

 available. Crucibles made of platinum, gold, silver, nickel, fused quartz, and 

 an alloy consisting of canadium i part, palladium i part, platinum 2 parts, and 

 nickel 6 parts, were subjected to comparative tests. The tests consisted in sub- 

 jecting the crucibles to a high temperature for a period of 32 hours, and im- 

 mersion in strong acids, (hydrochloric, sulphuric and nitric), and determining 

 their resistance to halogens, alkalies, etc. In the first test it was found that 

 platinum gave the poorest results, losing 0.14% of its weight, as compared with 

 silver 0.017%. In the second test (with acids), platinum showed to best results, 

 but gold, canadium alloy and quartz also showed good results. The highest 

 figure was 0,04% of loss for gold in hydrochloric acid, and 0,02% loss for the 

 canadium alloy in nitric acid; silver showed better results in hydrochloric acid 

 than did gold, but showed a greater loss in sulphuric acid, while nickel gave 

 poor results with both. The experiments seemed to show that the canadium 

 alloy was the best general substitute for platinum, its resisting powers being 

 but slightly less. The melting point of the alloy is about 1570° C. and its cost 

 only one-half that of platinum. 



Precipitant for Sugars, Starches, etc. 



W. Schulte, in Chem. Zeit., 1^17, 41, states that an ammoniacal lead acetate 

 solution may serve as a precipitant for sucrose, invert sugar, dextrose, lactose, 

 dextrins and starch from their aqueous solutions. Gum arabic, gum tragacanth, 

 albumin, casein, pepsin, peptone and gelatin are also precipitated by this reagent. 

 Citric, tartaric, malic, tannic, gallic and succinic acids and pyrogallol are pre- 

 cipitated by solution of lead acetate. Benzoic, salicylic and picric acids however 

 are only precipitated by ammoniacal lead acetate solution. Phenol also is pre- 

 cipitated by the latter solution. It is important that the ammoniacal lead acetate 

 solution be freshly prepared, as it undergoes decomposition very rapidly. It is 

 made by mixing 100 mils of an aqueous saturated solution of lead acetate with 

 26 mils of water, and 8 mils of ammonia water, specific gravity 0,910. 



It is stated that i part of gum arabic or phenol in 20.000 parts of water, 

 will show a precipitate or turbidity with the reagent, while with sugars the limit 

 is said to be about i in 10,000 parts. The precipitates obtained may be further 

 treated by washing with very dilute ammonia water, then dried and weighed. 

 The precipitate may also be ignited and the residue of lead oxide weighed. 

 Factors are given for obtaining the quantity of substance present, either from 

 the weight of the precipitate or from the weight of the lead oxide. The follow- 

 ing are examples : Sucrose Gum Arabic Phenol 



From weight of precipitate 0.1727 0.2564 0.2636 



of lead oxide 0.2386 0.3703 O.3125 



It is suggested that as glycerol is not precipitated by this reagent, that the 

 latter may afford a means of separation of glycerol from sugars and other like 

 bodies, in wines and allied liquids. 



