The first I accomplished by retaining the carbonic acid until heat was applied, the latter, by manufacturing a more economical acid than foreign cream tartar. After more than a thousand experiments covering a period of six months, I discovered by exsiccating ammonia alum I provided an article that would possess the necessary qualities. This article no more resembles the ordinary alum than charcoal resembles wood--it is light, porous, friable, and without taste. This article, under the influence of heat, combines with the soda and forms Glauber salts. In baking, the alum unites with the soda, just as cream tartar unites. In using the baking powder prepared according to my formula, you have in your bread Glauber instead of Rochelle salts. To your physician apply for his opinion of these salts; I will bow to his decision. Another false impression these zealous guardians of the public health have made is, that I used the exsiccated alum because it was cheap. The fact is that when I commenced its use it cost by the thousand pounds 12 per cent. more than the best cream tartar is worth to-day, and 33 per cent. more than average price of that article for the past year. I have since reduced the cost of manufacturing, and as I did so, correspondingly reduced the price of powder to the public. I regard the quantity of soda in cream tartar baking powders as very objectionable; they generally contain about 33 per cent. In my powder only 20 per cent. The prejudice in the public mind against alum, originated in the habit of the English bakers buying damaged flour, and by the addition of crude alum, made their bread in appearance equal to that made from best flour. Against this practice laws were enacted, not so much against the qualities of alum, as against its use in covering up a fraud in flour. This was the common potash alum and uncombined with any carbonated alkali, and it passed into the stomach unchanged. It is a trick--for it deserves no better name--of our rivals to show by chemical analysis that my powder contains alum, but are careful neither to state the kind nor the change it undergoes in baking. The manufacturer who knowingly misrepresents the goods of a rival, may well be doubted when he speaks of the quality of his own.