. A. Blair — Chromium and Aluminium in Steel and Iron. 421 



Art. XLV .—Estimation of Chromium and Aluminium in Steel 

 and Iron ; by Andrew A. Blair. 



Having had occasion, several years since, to examine a num- 

 ber of samples of so-called "Chrome-steel," for the percentage 

 of chromium, I began by search in-' for chis element in the resi- 

 due left after acting on the steel with dilute IK'!, as, in the case 

 of cast-iron, this plan is recommended.* Failing to find it here, 

 except in very small amounts, there seemed to remain two 

 methods of procedure : the first heimr to fuse the sample with 

 Na 2 C0 3 and KN0 3 , either directlyf or after oxidizing % by 

 HN0 3 and evaporating to dryness; the second, to treat the 

 solution of the "steel containing the iron as a ferric salt, with 

 KHO, Na 2 C0 3 or Na 2 CO ? , and NaC 3 H 3 2 , in excess, and in 

 - or acetic acid solution oxidizing the Cr 2 3 to 

 Cr0 3 , by means of Br, CI, PbO a or KMnO,. which combines with 

 i as a soluble alkaline chromate, while in the cold or 

 upon boiling, the iron is precipitated as hydrated sesquioxide 

 or basic acetate.§ While both of these general methods will 

 undoubtedly give good results, when large amounts of chromium 

 are present, so that small amounts of the original substance can 

 beoperated upon, tiny [.resent many objectionable features when 

 the percentage of chromium is small, and the amount of steel 

 or iron that must necessarily be used is correspondingly large, 

 jipal objections are, in the first method, loss by spirt- 

 lg fusion, and in both, the difficulty of washing the 

 linous precipitate of iron free from alkaline chromate. 

 A third general method, viz : separating the Cr 2 3 from the 

 Fe 2 3 by means of C 4 H 6 6 , NH 4 HO, and NH 4 HS, exactly 

 as in the separation of A1 2 8 and Fe 2 3 , might be added, but 

 the difficulty of washing such a mass of ferrous sulphide seemed 

 quite impracticable, and the method was not even attempted. 



By means of barium carbonate, Cr 2 3 may be perfectly pre- 

 cipitated, ! a > the -reat mass of the iron, 

 which in a - lution of the steel would exist 

 as a ferrous salt. Following out this plan the result was the 

 following method. 



Five grams of borings or drillings are weighed out into a flask 



ing duri 



[ineral Analysis 



• -. Rendus, i 



I Rose, fi h'im Anal. Quant., p. 513. Fresenius, Quaot. Chem. Anal 



Sci.-Tuikd Series, Vol. XIII. No. 7s.__J„e, 1ST". 



