HC1 diluted with three to four times its volume of water poured 

 in, and the flask closed with a rubber stopper, provided with a 

 valve, such as is used in dissolving iron wire in volumetric 

 analysis. Heat is applied as required, and, when all the steel 

 is dissolved, a solid stopper is quickly substituted for the one 

 with the valve, and the flask and contents cooled. When cold, 

 the solution is diluted with cold water until the flask is about 

 three-fourths full, and a slight t-weess of BaC0 3 added with con- 

 stant agitation. The BaC0 3 should be free from BaS0 4 , as it 

 obscures the reaction, and too great an excess should be avoi- 

 ded.* The flask should be thoroughly shaken several times, 

 loosening the stopper occasionally to allow the C0 2 to escape, 

 and allowed to stand over night. ' It is then filtered as rapidly 

 as possible, the flask rinsed out several times with cold water, 

 and the precipitate on the filter (consisting of all the Cr 2 O s , 

 the residue from the steel insoluble in dilute HC1, some Fe 2 O s 

 and the excess of BaC0 3 ) washed well with cold water. The 

 filter is then punched and the precipitate washed into a small 

 clean beaker, the portion adhering to the sides of the flask dis- 

 solved in HC1, which is poured on the filter and the filter 

 cleared from any Fe 2 3 by HC1 and thorough washing with 

 hot water. f If sufficient HC1 has not been used in <■] 

 flask and washing filter, enough is now added to di 

 the Fe 2 3l Cr 2 3 , BaC0 3 in the beaker, the solution diluted, 

 boiled and the Fe 2 3 and Cr 2 3 precipitated by NH 4 HO, the 

 boiling being continued until all smell of NH 4 HO has disap- 

 peared. This precipitate is filtered and washed thorough!} mm 

 hot water to get rid of all BaCl 2 ; dried and transferred to a pla- 

 tinum crucible, carefully separating the filter, which is ignited 

 and the ashes added to the precipitate (which should not be 

 heated). A mixture of three grams Na 2 C0 3 and one 

 KN0 3 is now added, and the whole fused carefully, the heat 

 being raised gradually until all the KN0 3 is decomposed. After 

 cooling, the fused mass is treated with hot water* and the solu- 

 ble portion containing the Cr as alkaline chromate, with the 

 excess of the alkalies, separated from the Fe^Og by filtration, 

 the precipitate and filter being thoi-ou«_dilv washed with hot 

 water. The filtrate is acidulated with HG1, and evaporated to 



* It is almost impossible to buy BaCO , free from BaS0 4 , the very best brands 

 bom 5-30 p. c. of BaSOY I prepare my own by dissolving BaCl ? in 



