Detection

The detection of the addition of very small quantities of bicarbonate of soda to beer is by no means an easy matter when the constant pres. ence of soda salts in beer ash is considered, and the very variable content of alkali in the waters used for brewing purposes. The ash of beer is of very variable composition, being obtained in part from each of the principal constituents which enter into the preparation of the drink, viz, the malt, the hops, and the water used in the brewing. The content of soda (Na2O) in the ash varies in different published analyses, from less than 4 per cent. up to 35 per cent. of the ash,1 and this without a sufficient proportion of chlorine to account for the large per cent. of soda as salt. The presence of any considerable quantities of carbonate in beer ash, however, is abnormal, and indicates the addition of bicarbonate of soda to the beer, the acetates, lactates, etc, formed from it being converted into carbonates by the process of incineration. So far as I have been able to ascertain, no carbonic acid has ever been found in the ash of normal beer, its alkalinity being due to the presence of alkaline phosphates. I have found no statement as to whether the ash of normal beer reacts acid or alkaline in any of the books on the subject except Eisner,2 who says it reacts acid. This must certainly be a mistake, for the ash of every sample I examined gave a strong alkaline reaction, requiring from 5 to 3.5cc. of decinormal acid for the neutralization of the ash from 100cc. of beer. Hassall3 says, on the other hand, "the alkalinity of the ash must be estimated" in determining whether some alkaline earth or alkali has been added.

In order to investigate this question I procured a sample of beer made in Lafayette, Ind., which was guaranteed to contain no bicarbonate of soda, and which, from my knowledge of the parties through whom it was obtained, I have every reason to believe to be a sample of perfectly pure beer.4

The complete analysis of this sample was as follows:

Several portions of 100cc. each were taken, various quantities of bicarbonate of soda added, and after solution each portion evaporated to dryness and burned to ash. The alkalinity of the ash was then ascertained, with the following results:

1See Wolff, Aschen-Analysen, p. 23. 2 Page 89.

3 Page 706.

4 A small quantity of rice grit was admitted to have been used in its manufacture.

From these results it will be seen that the alkalinity of the ash shows very plainly the addition of considerable quantities of bicarbonate, but small additions would not be detected in this way. Again, the books state that the addition of bicarbonate of soda can be recognized by the strong effervescence of the ash with an acid. This statement is based entirely upon theoretical grounds, which have been shown by later investigations to be fallacious. When the acidity of normal beer was supposed to be due chiefly to lactic acid, the formation of lactate of soda, which would be converted into a carbonate on ignition, would, theoretically, make an ash which would effervesce strongly with acid. But now that it is known that the acidity is due to acid phosphates, it is easily seen that the addition of bicarbonate would only tend to the production of neutral or alkaline phosphates, which would give no effervescence with acid. This is shown by experiments I made with the sample of normal beer. Several portions of 100cc. each were taken, and different quantities of bicarbonate of soda added, and when solution had been effected the beer evaporated, and the residue carefully incinerated. The test for the presence of carbonate was made very carefully, by pouring a few drops of water on the ash, and turning the whole into a test tube containing dilute acid.

It will be seen from the above that there was no carbonate in the ash until sufficient bicarbonate was added to the beer to neutralize all its acidity, leaving an excess of bicarbonate in the beer. In Nos. 4 and 5 the beer reacted alkaline before evaporation.

The same beer was allowed to stand until it had become quite sour and spoiled, when the above set of experiments was repeated, with the following results:

From the above results it would seem that the bicarbonate united by preference with the acetic and lactic acids formed rather than with the acid phosphates of the beer, though it would require more experiments on the subject to thoroughly establish this point. If such is the case, however, it will be possible to detect the addition of bicarbonate to a beer that has soured, though not to a normal beer. The smallest quantity used in practice, according to the Brooklyn report, is one ounce to a half a barrel, which would be about 1 to 2,000, while the addition of .1 gram to 100cc. would be 1 to 1,000. Girard1 gives as a test for the addition of bicarbonate of soda to ciders the following procedure : Decolorize with bone black, evaporate to dryness, treat the residue with alcohol, which dissolves the acetates, which can be detected in the alcoholic solution. I have tried this test with very indifferent results, as I find the alcohol dissolves so much other matter from the dried residue that it is difficult to detect the presence of acetic acid in small quantities. The distillation of the beer in a current of steam2 after the addition of phosphoric acid offers a better method for the separation of acetic acid, which may be searched for in the distillate, and if found to be present in any quantity, while the acidity of the beer itself is normal or below normal, the addition of bicarbonate of soda will be pretty well established. In this way I established the fact of the addition of bicarbonate in Nos. 4814 and 4816, which were the only samples of which I could be positive; and although I strongly suspected several of the other samples, owing to the difficulties of the test I would not pronounce positively upon them.