M. Scheffer on Glucina and its Compounds. 455 



In a contribution on glucina and its compounds*, Scheffer 

 describes a method which he has used for preparing pure glucina. 

 The method was originally suggested, but not actually tried, by 

 Debray, It depends on the fact that when metallic zinc is in- 

 troduced into a solution of sulphate of alumina, sulphate of 

 zinc is formed, along with basic sulphate of alumina M'hich pre- 

 cipitates. The precipitation of the latter is complete if the solu- 

 tion be not too concentrated. Sulphate of glucina, treated in an 

 analogous manner, is decomposed with formation of the bibasic 

 sulphate, which remains, however, completely dissolved. 



To prepare glucina, beryl is mixed with fluor-spar, the mixture 

 digested at a gentle heat with sulphuric acid, and ultimately 

 heated to dull redness in a crucible in order to expel fluoride of 

 silicon and the excess of acid. The residue is then dissolved in 

 water containing sulphuric acid; and in order to remove the 

 greater part of the alumina, sulphate of potash or sulphate of 

 ammonia is added, which forms alum with the sulphate of alu- 

 mina. "When the greater part of the alum has been removed 

 by crystalhzation, the mother-liquor is greatly diluted, metallic 

 zinc added, the mixture allowed to stand two or three days, then 

 heated and filtered. To the mixture a quantity of sulphate of 

 potash proportionate to the zinc is added, to form with the sul- 

 phate of zinc a double salt which crystallizes out. To remove 

 the rest of the zinc, sulphuretted hydrogen is passed through the 

 solution, acetate of soda in excess having been previously added. 

 The filtrate is then neutralized with ammonia, and the glucina 

 precipitated by means of sulphide of ammonium. By this me- 

 thod 11 to 13'5 per cent, of pure glucina was obtained from 

 common beryl. 



Scheffer prepared some pure phosphates of glucina, and deter- 

 mined from them the equivalent of glucinum. He considers that 

 glucina is a protoxide, BeO, and not a sesquioxide, Be^ 0^ ; on 

 this supposition his experiments led to the number 12'64 for the 

 equivalent of glucinum. 



Wohlerf describes the following easy method of preparing me- 

 tallic chromium. It depends on the reduction of the sesqui- 

 chloridc by means of zinc. 



One part of sesquichloride of chromium is mixed with two 

 parts of chloride of sodium and potassium (a mixture consisting 

 of nine parts chloride of potassium to seven parts chloride of 

 sodium), the mixture ])laced in an ordinary crucible, two parts 

 of granulated zinc placed in it, and the whole covered with a 

 layer of the mixed chlorides. The crucible is then lieated to 

 redness, and as soon as a bubbling sound is heard, which shows 



* Licbig's Annalen, February 1859. f Ibid. August 1869. 



