The Following is taken directly from: Farmers Bulletin 393; an official U.S. Government Bulletin:[2]

Colds and coughs are among the most common ailments of childhood and youth, and many special mixtures have been devised and placed on the market for treating them. These concoctions usually contain one or more habit-forming drugs, as is clearly shown by the following examples: [Included in the list is] Kohler's One-Night Cough Cure (morphin sulphate, chloroform, and cannabis indica)"
Chloroform and Cannabis Indica (dealt with elsewhere) we will ignore for now. However, the use of Morphine in cough syrups is another matter altogether. The question is: Was the use of morphine justifiable? The answer seems to be NO---it was not!

This, especially as codeine (which like morphine is and opium derivative) would later on become a common ingredient found in most cough syrups, needs some further explanation. When dealing with quack or dangerous medicines, one must always take the technology of the times into account and ask the questions:

" Was the drugs benefits worth it? That is, did it actually treat the disease to the point that its harmful side-effects were worth it?
" Given the medical technology, were there any other (safer) alternatives?

If one were talking about Kohler's formula back in 1875, I would say yes to the first and no to the second. But, by 1910 (the year the bulleting came out) the answers would be totally different. True its close chemical cousin codeine would soon come into widespread use, but ONLY because of other politically motivated reasons. While alcohol could be used to replace Chloroform (ask any drunk during prohibition), numerous other ingredients would soon no longer be available to pharmaceutical manufactures. For example: Cannabis (aka the 'killer weed') would soon come to be associated (thanks to the reefer madness era), with axe murders and scantly clad-coeds jumping out of windows. Thus its reputation, not to mention, the passage of the anti-medical marihuana laws, made it unavailable for use in cough syrups.

It was for this reason, and only for this reason, that codeine, at that time a little know drug, and thus not associated with opium in any way, made its way into cough syrups.

But all that would be in the future, in 1910 numerous safer formulary ingredients were available and thus should have been used. Its use of morphine therefore is what makes Kohler's One-Nigh-cough Cure, into an overly dangerous medicine and thus (at least in the authors opinion) a Quack product.

[2] -- U.S. Department of agriculture -- Farmers Bulletin 393. "Habit-Forming Agents: Their Indiscriminate Sale And Use A Menace To The Public Welfare," by H.W. Wiley.