320 Scientific Intelligence. 



The sodium mercuric iodide solution is of considerable interest, 

 as it is heavier than even methylene iodide. Although water 

 produces in it a precipitate of mercuric iodide, it dissolves with- 

 out change in alcohol and many other organic liquids. — Comptes 

 JRe?idus, cxli, 385. h. l. w. 



3. Hydrolysis of very Concentrated Ferric Sidphate Solu- 

 tions. — It has been observed by Recottra that a concentrated 

 solution of ferric sulphate made by dissolving the anhydrous 

 salt in its own weight of water is completely decomposed when 

 it is placed in contact with acetone for several days. The 

 products are sulphuric acid, which dissolves in the acetone, and a 

 basic ferric sulphate which separates in the solid form. The 

 latter is yellowish white in color, is soluble in water, and has a 

 composition represented by the formula 6Fe 2 (S0 4 ) 3 .Fe 2 3 . H 2 0. 

 The same solid is formed without the use of acetone when a 

 strong solution of ferric sulphate is placed in a well-stoppered 

 flask and allowed to stand for a longer time. With solutions of 

 the strength given above, the deposit begins to form after about 

 twelve days and extends through the liquid in about a month. 

 With stronger solutions the precipitate is formed more rapidly 

 and abundantly, while with solutions slightly more dilute no basic 

 salt separates. The deposit is formed most rapidly at 20°, and 

 more slowly as the temperature is kept lower. — Comptes Rendus, 

 cxl, 1685. h. l. w. 



4. Separation of Gold from the Metals of the Platinum 

 Group. — Jannasch and von Moyer have found that gold is 

 precipitated quantitatively by a salt of hydrozine in any kind of 

 solution. This reagent, however, on account of its powerful 

 reducing action does not serve to separate gold from the metals 

 of the platinum group, although it is thus separated satisfactorily 

 from potassium, sodium, barium, strontium, calcium, magnesium, 

 aluminium, chromium, zinc, manganese, iron, uranium, nickel, 

 cobalt, cadmium, mercury, lead and copper. Gold is precipitated 

 by a hydroxylamine salt in acid solution somewhat slowly, and 

 not below a temperature of 80°. Preliminary tests indicate that 

 hydroxylamine hydrochloride is a satisfactory reagent for the 

 separation of gold from palladium, platinum, iridium and rho- 

 dium, as well as from ruthenium and osmium. — JBerichte, xxxviii, 

 2129. h. l. w. 



5. Determination of Sugar with Fehling^s Solution. — On 

 account of difficulties encountered in determining small quantities 

 of sugar by Fehling's volumetric method, Lavalle has modified 

 this by carrying it out in the presence of an excess of caustic 

 soda, so that the cuprous oxide produced remains in solution, and 

 the change in color is more readily detected. The operation is as 

 follows : In a porcelain dish of 200 cc capacity are placed 5 or 10 cc 

 of Fehling's solution, 30 cc of sodium hydroxide solution (1 : 3), 

 and 50 or 60 cc ol distilled water. The liquid is then heated, and 

 when it begins to boil the solution to be tested is gradually added. 

 The operation is finished when the last drop causes the blue color 

 of the Fehling's solution to disappear. — Berichte, xxxviii, 2170. 



h. l. w. 



