I found this interesting with all the labeling laws already enacted, or desires from different groups who want to know what is in food being sold today. Since this was printed in 1889, it seems even back then honest labeling on ingredients was a concern. The authors argued for the requiring of manufacturers to use a label giving the composition of the item being sold, in this case baking powder, and to answer the question, What is in your baking powder?
The authors further argue that fertilizer (for farming) must have 'truth in labeling', so why can't consumers (mainly housewives back then) have the same thing for baking powder: purchase a product that they know exactly what is inside of it, and can therefore make an estimation of the purity and function in cooking and baking. Also, if two items are sold at the same price, one item shouldn't be a watered-down version just so the manufacturer can make a tidy profit.
The book states:
A substance sold as a fertilizer must have its composition, in so far as is necessary for its valuation for such a purpose, plainly stated on the bag in which it is sold, because the purchaser has no means of ascertaining this value by any ordinary or simple test. Otherwise the manufacturer could easily impose upon him by selling him a substance which resembled a fertilizer in general appearance, but contained no constituent of any value whatever for fertilizing purposes. The purchaser of a baking-powder receives a white powder which may contain various substances more or less valuable for the desired purpose, or of no value whatever, or perhaps even injurious to the health.
The housewife surely deserves protection against swindling as much as the farmer, and she has no better means for ascertaining the strength and quality of the baking-powder she buys than the latter has for learning the strength of his fertilizer. The verity and accuracy of the analysis stated on the label should be insured, as in the case of the fertilizer, by its being performed by sworn analysts. If such a regulation were enforced, people would soon inform themselves of the respective merits of different varieties, and the further requirement of a certain standard of strength, as suggested by Professor Cornwall, would probably be unnecessary, as they would learn to interpret the analysis, and a powder made up with 50 per cent. [sic] of starch, for instance, would have to be sold cheaper than one made with 10 per cent., or not at all.
Interesting stuff here, and still relevant, almost 125 years later.
U.S. Department of Agriculture. Division of Chemistry. Foods and Food Adulterants. Investigations Made Under Direction of Dr. H.W. Wiley, Chief Chemist. Part Fifth: Baking Powders. (Bulletin No. 13) Washington: Government Printing Office, 1889.