Stiidy of Spirogyra nitiJa. 207 



Analysis of the Ash. 



During the preparation of considerable quantities of ash, 

 the apparatus best suited to obtain a perfect combustion 

 was found to be a broad platinum dish, over which was 

 suspended a wide glass tube a little longer than an ordinary 

 lamp-chimney, (Schultze method.) The air current so pro- 

 duced causes an even and rapid oxidation of the carbon, 

 with the expenditure of a minimum amount of heat. The 

 ash so burnt was of a pale gray color and perfectly homo- 

 geneous. It was preserved for analysis in closely stoppered 

 weighing bottles. 



The method of analysis was essentially that of Bunsen 

 as described in his " Aschen Analyse." According to 

 this analyst the weighed ash should be brought into a 

 cylinder with water, and the latter saturated with carbon 

 dioxide until the liquid becomes colorless. The solution 

 should then be transferred to a platinum dish and evapo- 

 rated to dryness on the water bath, heating finally at 160 C. 

 By this means all the lime should exist as neutral carbon- 

 ate, and a water extraction should give only the salts of the 

 alkalies. 



The aqueous extract was made up to a known volume 

 and divided into five portions. In the first the chlorine 

 was determined, in the second the sulphuric acid, in the 

 third the alkalies, in the fourth phosphoric acid, and in the 

 fifth carbon dioxide. The insoluble residue was analyzed 

 for silicic acid, phosphoric acid, calcium, magnesium, iron 

 and aluminium, sulphuric acid and carbon dioxide. 



An analysis of Spirogyra ash, conducted as above out- 

 lined, gave the following percentage composition : 



1. 11. in. 



Si0 2 529 5-38 5-3° 



S0 3 9-13 9- 1 1 



CI 24.24 24.08 24.51 



P 2 5 0.898 0.91 



CaO 9 or 9-20 



MgO 2.21 2.18 



