Sept., 191 j
T H E J O U R N A L OF I X D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
with dilute hydrochloric acid, which on such low figures as obtain with percentages of AlaOa in steel is certainly negligible. The above assertion has been borne out in practice, by adding just enough aluminum to deoxidize the steel, avoiding an excess. By employing the method as given below on such steels, all of the aluminum was found to be in the insoluble residue as oxide. The method is as follows: Dissolve j o grams drillings in a mixture of zoo cc. strong hydrochloric acid and 300 cc. water a t gentle heat, bring to a boil, allow insoluble matter t o settle and filter through a double Baker & Adamson grade A paper or Schleicher & Schull S o . j 9 0 , and wash with hot dilute ( I : 2 ) hydrochloric acid and hot water. Ignite the residue in a platinum fusion crucible. Add ‘/2 gram pure sodium borate’ calcined, and heat gently a feu- minutes till A12O3 is in solution. Now add 5 grams pure sodium carbonate and fuse a few minutes longer until all is melted and in a state of quiet fusion. Dissolve fusion in hot water in a platinum or nickel dish, and determine &03 in the usual manner. I n the filtrate the ,41 is directly precipitated as phosphate according to Wohler, as described by Blair. The precipitate is dissolved in HhTOs, any chromium oxidized by boiling with KMn04, and the A1 precipitated from the Cr, Cu, etc., with ammonia. This precipitate is dissolved in HCl, evaporated to dryness to separate SO;, and in the filtrate the A1 is again precipitated as phosphate as before SAUCON PLAKT, BETHLEHEM STEEL COMPANY F. 0 . KICHLINE SOUTH BETHLEHEM, P A . ,
While the use of concentrated hydrochloric acid as applied to bread examination had been tried by the writer, some little trouble was experienced due to progressive precipitation of proteids. A seemingly more preferable procedure consisted in the use of dilute HCl, the method finally adopted being as follows: Twenty-five grams of the air-dry ground bread were digested for 2 to 4 hours on the top of the water bath a t gentle heat with 2 0 0 cc. of j per cent HCl, the mixture being well stirred a t intervals. After cooling, the clear extract was decanted through a folded filter, the residue washed two or three times with warm water, and the filtrate precipitated as usual with BaC12. As a rule, the precipitated sulfate was clean. In those cases where it showed contamination with organic matter, the BaSOa, after ignition and weighing, was treated in the Gooch with a few cc. of acidulated hot water, followed by a second ignition and weighing. While time did not permit any elaborate confirmation of the accuracy of the above procedure, it seems evident a t least that the application of the general principle of direct’ extraction of SO3 in connection with materials of this nature is necessary for truthful results. I n view of present ‘commercial practices i t would seem that the matter of an accurate method in this connection is worthy of special study. N.
H.
CHAKLES D. HOWARD
LABORATORY OF HYGIENE
BOARDOF HEALTH CONCORD, N. H . , May 15, 1915 STATE
April 19, 1915
NOTE ON THE DETERMINATION OF SULFATES IN BREAD In view of the adoption by a certain prominent baking concern of the use of calcium sulfate as an auxiliary to the leavening process, the writer has recently had occasion to estimate the proportion of sulfates existent in a number of samples of bread. It was soon found that for purposes of accurate comparison between the sulfated and non-sulfated loaves the ordinary procedure, based upon precipitation of the ash solution, was practically worthless. Ignition with calcium acetate, according t o the A. 0. A. C. official method, afforded results apparently too high, due, i t was assumed, to oxidation of organic sulfur. Extraction of the charred ash promised no better, the results thus obtained being exceedingly erratic. The procedure finally followed consisted in direct precipitation of the filtered extract of the bread as obtained with dilute hydrochloric acid. While the literature was not consulted at the time, the writer has since been interested to note that other workers have encountered similar difficulty in connection with the estimation of sulfates in flour. Thus O‘Sullivan (Analyst, 1914, p. 42j) refers to the unreliability of SO3 determinations based upon the use of the ash for liquors, his conclusion being that sulfuric anhydride is expelled on ignition in the presence of any appreciable amount of magnesium, unless a carbonate is present. In the same number (p. 429) Cripps and Wright, working upon flour, ascribed low results as obtained by them to the presence of acid phosphates, developed during ashing. The method followed by the latter chemists consisted in the cold extraction of IOO grams of the flour with 1000 cc. of I per cent acetic acid, the decanted extract being acidulated with HCl, boiled, nearly neutralized, and after removal of proteids with Almen’s tannin reagent, precipitation with BaClz as usual. I n a more recent paper upon the same subject Elsdon (Analyst, 1915, p. 142) describes a procedure nearly identical with that as followed by the present writer. Elsdon’s process consists in the extraction of I O grams of flour with 25 cc. concentrated HCl in a beaker on the top of a water bath, the filtered extract being directly precipitated with BaClz after dilution with IOO cc. of water. Results thus obtained on normal flours were distinctly higher than by the acetic acid extraction. 1 It is generally impossible to decompose all the carbonate fusion alone.
-41203
b y a sodium
THE EXACT DILUTION OF LIQUID REAGENTS BY FORMULA Editor of the Journal of Industrial and Engineering Chemistry: That “there is nothing new under the sun”-at least as regards mathematical formulas-finds still further illustration in a note appearing in the April issue of the Journal, under the caption “To Change the Specific Gravities of Solutions.” Here Mr. Bovard suggests a formula for determining the amount of water to be added to a given volume of solution of specific gravity S to bring such t o a specific gravity SI. I n an article under the above heading in the J . Am. Chem. Sac., 19 (1897), 587 the writer gave the complement of the above formula, i. e . , to what volume (Vt) must a given volume (V,) of solution of specific gravity SIbe diluted in order to secure Vx(S1-I)
a density of S2, the formula being Vt =
~
-
s2-I
~
~
~
Vt(S2 - 1) And conversely, the formula * V x= __gives the SI - I amount of solution (V,) to be diluted to a required volume Vf, where the specific gravities are respectively SIand S2. A third formula represented the problem involved where it is desired to dilute to a certain specific gravity with some reagent other than water, it being directed to first consider water as the diluting agent and find Vi as above. Then, if Sa is the specific gravity of the diluting reagent,
vL x-
Sa
=
the volume of the
same necessary to be added to V, to give a liquid of the specific gravity required ( S P ) . CHARLESD. HOWARD STATE LABORATORY O F HYGIENE CONCORD, N.
H . , April 26, 1915
REAGENTS FOR USE IN GAS ANALYSIS I. ALKALINE PYROGALLOL-A CORRECTION On page j g j of the article under the above title, THISJOURNAL, 7 (I~IS),j 8 7 , the statement “by dissolving 87.5 g. of stick sodium hydroxide in goo cc. of water” should read “by dissolving 8 7 . 5 g. of stick sodium hydroxide in IOO cc. of water.” CORNELL UNIVERSITY N. Y . , July 31, 1915
ITHACA.
R. P. ANDERSON
.
