This 28-page PDF download (with 10 illustrations) is a source of information beyond the average online vinegar-making tutorials. Here is how the bulletin describes itself...
"Vinegar can be made from any fruit, or, in fact, from any material which contains enough sugar and is in no way objectionable.
Whether it is done on a small scale in the home, or on a larger scale on the farm, or in a still larger scale in the factory, the production of vinegar is the result of two distinct fermentation processes—an alcoholic fermentation followed by an acetic fermentation.
By using the materials and following the methods discussed in this bulletin, vinegar of good quality may readily be made from apples, peaches, grapes, and other fruits, large quantities of which are wasted each year in the United States."
This bulletin discusses the making of vinegar using apples, grapes, oranges, peaches, persimmons, pears, berries, honey, maple syrup, watermelons, grains, and molasses. Fermenting, filtering, clarifying, aging, pasteurizing, and packing are all covered. In addition to simple home vinegar production, a larger-scale, continuous-barrel process is explained. For commercial vinegar production, the bulletin describes how to make and use a "quick vinegar generator."
There is also a discussion of "Causes of Failure" and "Animal Parasites" (vinegar eels and vinegar mites).
Testing for acid strength of the vinegar is covered near the end of the bulletin. However, the testing process in 1924 seems better suited to someone with a scientific or laboratory background. The bulletin ends with "Federal Regulations Governing The Manufacture And Sale Of Vinegar."