THE ANALYST. 5 ALUMINA AS A NATURAL CONSTITUENT OF WHEAT FLOUR. BY W. C. YOUNG, F.C.S. (Read at Meeting, Nouember, 1887.) IN a paper read before the Society last June, and published in the August number of the ANALYST, I gave an acconnt of some experiments with the logwood test, the results of which seemed to indicate that alumina was a natural constituent of wheat flour, and, further, that it was confined to ths gluten, the starch being quite free from it. I n the discussion which followed, our President pointed out that it was generally supposed that alumina was not a natural constituent of wheat flour, and that when found it was ascribed to accidental impurities or purposely added alum. I find also that in the dis- cussion of a paper by Wanklyn at the first meeting of this Society, Mr.Allen similarly expressed himself, but Dr. Dupr6 mentioned that in conjunction with Dr. Odling he had made many analyses of wheat, and had found minute quantities of alumina in every sample. Recently Yoshida has communicated a paper to the Chemical Society on ‘‘ Aluminium in the ashes of flowering plants,” in which he shows that alumina iS a normal con- stituent of wheat and other cereals. Soon after the reading of my last paper, 1 made a quantitative experiment on wheat flour, the result of which not only confirms Yoshida’s work, but shows further that the whole of the alumina is contained in the gluten. The flour used was the best quality Vienna, containing -7 per cent. of ash, and a3 near as I could ascertain about 8 per cent. of gluten. I obtained from 100 grammes of this flour, by a process I shall presently describe, 90075 gramme of phosphate of alumina, The gluten was separated by washing in a muslin bag in the usual way, and when dried contained 1.26 per cent.ash; 20 grammes of this dried gluten, finely powdered, was then treated with about 250 C.C. of a mixture of equal volumes of acetic acid and water, and heated in the water bath for about twenty-eight hours. By this time the mass had become quite liquid, the gluten having lost its firmness in the same way that gelatin does under similar circumstances. After standing a short time the liquid was poured off, and the sediment further treated with weak acetic acid twice, and the three portions of liquid evaporated t o dryness, the sediment being rejected. I n this way I think that any extraneous earthy matter present in the gluten was separated, and, there- fore, only the natural alumina retained, The dried residue was then burnt to a perfect ash, the ash dissolved in dilute6 THE ANALYST.hydrochloric acid and filtered, the insoluble matter being well washed and weighed. The insoluble matter thus obtained weighed only -009 gramme, and of this -0075 was silica. The insoluble matter was then fused with about twice its bulk of mixed alkaline carbonates, dissolved in dilute hydrochloric acid and filtered. This filtrate was added to the acid solution of the ash, evaporated to dryness, redissolved in a small quantity of dilute hydrochloric acid and filtered. The filtrate was then boiled, and cautiously added to 25 C.C.of a saturated solution of pure caustic soda, also boiling, and the whole kept boiling for a few minutes. It, was then filtered, and the precipitate washed, the filtrate made slightly acid with hydrochloric acid, about 6 C.C. of a saturated solution of sodium phosphate added, and finally a slight excess of ammonia. After boiling for about ten miiiutes, the precipitate of phosphate of alumina was collected and weighed. I may mention that the process I have just described has been in use for some years now in my laboratory for determining alumina in bread and flour, and is really an improvement on a modification of Normandy’s old process which I suggested some years back. The points to be observed as essential to success are, first, the fusion with alkaline carbonates of the ash insoluble in hydrochloric acid, as I have repeatedly found that hydrochloric acid does not dissolve the whole of the alumina in the ash; second, keeping the solutions down to the smallest possible bulk; and third, the employment of B saturated solution of soda.I n this way I obtained ~0185 gramme of phosphate of alumina from 20 grammes of gluten. Now as the flour contained S per cent, of gluten, and gave originally *0075 per cent. of phosphate of alumina, 20 grammes of gluten would be equivalent to 250 of flour, which would yield .01S75 of phosphate of alumina. So that practically I obtained the whole of the alumina of the flour in the gluten. As in the process of washing the starch from the gluten a large proportion of any foreign earthy matter that may have been present must have been separated, and any remaining eliminated by dissolving the gluten in acetic acid, there can be no doubt that the alumina obtained in this experiment was present as a natural constituent of the flour, and I think further that the interest- ing fact is established that the bulk of it is associated with the gluten.