422 Mr. Rowney^s Analysis 



b. Determination of Lime. 



The acid filtrate from the silicic acid was neutralized by 

 ammonia, then slightly acidulated with acetic acid and pre- 

 cipitated by oxalate of ammonia, and the oxalate of lime con- 

 verted into carbonate in the usual manner. 



I. 2-1890 grms. of glass gave 0-4203 grm. of carbonate of 

 lime. 



II. 2*1284 grms. of glass gave 0*3843 grm. of carbonate of 

 lime. 



c. Determination of Alumina and Sesquioxide of Iron. 



To the liquid filtered from the precipitate of oxalate of lime 

 {b.), containing a large quantity of chloride of ammonium, am- 

 monia was added in excess, by which alumina and sesqui- 

 oxide of iron were precipitated and the oxide of manganese 

 and magnesia were retained in solution. The joint precipi- 

 tate of alumina and sesquioxide of iron was collected, washed, 

 ignited and weighed ; then dissolved in hydrochloric acid and 

 thrown down with potassa, which kept the alumina in solu- 

 tion. The precipitate of sesquioxide of iron (thus obtained), 

 once more dissolved in hydrochloric acid and reprecipitated by 

 ammonia, was now collected, ignited and weighed ; the differ- 

 ence in the amoimt of the two weighings gave the amount 

 of the alumina thus : — 



2-1890 grms. of glass gave 0-0096 grm. of mixed oxides 

 and 0-0029 grm. of sesquioxide of iron ; the difference, 0-0067 

 grm., is the amount of alumina. 



d. Determination of Oxide of Manganese. 



This oxide was thrown down by carbonate of soda as car- 

 bonate of manganese, from the filtrate, separated from the 

 oxide of iron and alumina (c.) ; the precipitate was washed, 

 dried, ignited, and calculated as the compound oxide and ses- 

 quioxide of manganese (MngOJ. 



I. 2*1890 grms. of glass gave 0-0114 grm. of the above- 

 named double oxide. 



II. 2-1284 grms. of glass gave 0*0160 grm. of the double 

 oxide. 



€. Determination of the Magnesia. 



The filtrate from the carbonate of manganese [d.) was pre- 

 cipitated by phosphate of soda ; the phosphate of magnesia 

 and ammonia was washed, dried, ignited and weighed as pyro- 

 phosphate of magnesia. 



I. 2-1890 grms. of glass gave 0-0127 grm. of pyrophosphate 

 of magnesia. 



