and Laboratory Methods. 1497 



to the amount of phosphoric acid present ; that is, when there is a large amount 

 the drop must be large, so as to permit of sufficient heating. It is better under 

 such conditions to employ two operations to remove the phosphates rather than 

 attempt it in a single one. A small test tube will generally prove more satisfac- 

 tory than a slide or watch glass. 



GLUCINUM. 



A. Ghicmnm in Simple Substances. 



Add ammonium hydroxide and ammonium carbonate (see page 1828) in 

 excess, glucinum hydroxide is dissolved (also U, Zn, Cd, and perhaps Mg). 

 Decant or filter, and to the solution add ammonium chloride in moderate amount, 

 evaporate, and ignite gently until all ammonium salts are removed. The residue 

 is dissolved in dilute sulphuric acid, a little sodium acetate and a trace of 

 mercuric chloride added. The preparation is then tested for glucinum with 

 potassium oxalate. Or, treat the residue with uranyl acetate and sodium acetate. 

 In the latter case Mg, Zn, Cd must be absent. 



B. Glucinum from Alagnesium. 



Add to the solution sodium hydroxide, warm, evaporate and take up with 

 water. Magnesium hydroxide is precipitated, the glucinum passes into solution 

 (also Zn and Al). 



Wash the precipitate and treat it with ammonium chloride, the magnesium 

 passes into solution and is tested with sodium phosphate and ammonium 

 hydroxide. 



The solution containing the glucinum is evaporated, extracted with hydro- 

 chloric acid and tested with potassium oxalate. 



C. Glucinum in Complex Mixtures. 



Remove any copper, etc., by iron foil. 



Add ammonium hydroxide and hydrogen peroxide. Warm for a time, then 

 evaporate. Repeat the treatment. Extract the residue with a solution of 

 ammonium carbonate. Fe, Mn, Co, Al and part of the Mg should remain 

 insoluble, while Gl, Zn, U, Mg will be dissolved. The solution is evaporated, 

 ignited, dissolved in dilute acid and tested with potassium oxalate ; or if much 

 magnesium is present, separate with sodium hydroxide as in B. 



MAGNESIUM. 



A. Magncsiiwi frot7i Glucinum, Zinc, Cadmiiwi, Alu?ninum. 



Precipitate with sodium hydroxide, warm, evaporate, and extract repeatedly 

 with water. Mg and Cd remain behind. Dissolve the residue in hydrochloric 

 acid and divide into two portions. Test one part for magnesium Avith sodium 

 phosphate, and the other for cadmium with sulphocyanate or oxalic acid. 



B. Magnesium ifi Complex Mixtures. 



Add ammonium chloride and ammonium hydroxide in slight excess, then 

 hydrogen peroxide, and warm. Evaporate and treat again. Extract the residue 



