198 ANNUAL OF SCIENTIFIC DISCOVERY. 



73° and 78°; oxide of zinc was not reduced at a temperature at 

 which ghiss fused. 



Experiments were also made on the chlorides and sulphides of 

 certain metals. Ciiloride of gold does not appear to [)e acted 

 upon below 200°, but at a higher temperature an explosion took 

 place; the action on chloride of platinum was strong at 85°, vio- 

 lent at 165° ; the chlorides of silver and lead require a red heat 

 for reduction. Sulphide of gold is reduced at 200°, and sulphide 

 of i»latinum at the ordinar\' temperature ; sulphuretted hydrogen 

 is formed in both cases. — Pogg. Ann. 



PROPERTY OF TEROXIDE OF THALLIUM. 



The teroxide of thallium mav be obtained as a dark-brown 

 powder b}^ digesting with heat freshly j)recipitated chloride of 

 thallium in a solution of hypochlorite of sodium containing an 

 excess of alkali. If a mixture of the dry teroxide and flowers of 

 sulphur is submitted to a moderate friction, it ignites with explo- 

 sion. AVhen, however, to the teroxide is added one-eighth its 

 weight of the product vulgarly known as golden sulphur, it is ob- 

 sei-ved that the igniti;)n requires less rubbing and takes place 

 without explosion. This mixture possesses the property of being 

 set on fire by the faintest electric spark, surpassing, in this re- 

 spect, the well-known mixture of equal parts of chlorate of potas- 

 sium and black sulphide of antimony. — Dingl. Polyt. Journ. 



MARGUEKITTE's METHOD OF REFINING SUGAR. 



It is M'ell known that the present method of manufacturing 

 sugar, notwithstanding the improvements it has received of late 

 years, does not allow the extraction of the whole of the sugar 

 contained in the beet-root, and tliat the residue contains about 50 

 per cent, of its weight of the substance to be obtained. The 

 combinations of barium and calcium with sugar, observed by M. 

 Peligot, and the discovery of osmose and dialysis by Messrs. 

 Graham and Dutrochet, have given rise to many attempts to ex- 

 tract from molasses the sugar which it contains in a non-crys- 

 tallizable form. 



Tiie method employed by M. Margueritte is to mix the molas- 

 ses with alcohol of 85° acidulated with 5 per cent, of sulphuric 

 acid. The precipitate which forms, and which consists mainly of 

 the sulphates of potassium, sodium, and calcium, is removed by 

 filtration, and to the liquor is added an amount of alcohol of 95° 

 equal to that originally employed. A supersaturated solution of 

 sugar is thus obtained, from which the sugar slowly deposits. To 

 hasten this operation a quantity of sugar is added to the solution, 

 and this addition determines the immediate separation of the 

 greater portion of the sugar dissolved. M. Margueritte claims to 

 obtain 35 to 38 kilos, of sugar from 100 kilos, of molasses, and 

 to increase the total amount of the yield from 24 to 26 per cent,— 

 Comptcs Rendus. 



