By the way when I said "later" the spirits were subjected to double-distillation, I meant, later in the 19th century, not later during the process when subjected to charcoal leaching. I obtained this information from Tanya MacKinnon's thesis on the historical geography of Canadian distilling in the 1800's, to which I've referred on the board before.
I believe Ms. MacKinnon did state that maple charcoal was used in the Canadian leaching vats.
She also said that the vats were dispensed with once distillers were able to rectify by further distilling the product (presumably in a second, rectification tower, she did as I recall refer to a second distillation after the first in a column still). What is called Bourbon steam, and probably more pertinently what is called highwines, in the 1870 NYT article probably corresponds to this later stage of the Canadian technology. Indeed, it is (more or less) the last stage, since it seems (per M. Jackson's studies and my own inferences) that the Canadian light whisky style was perfected by the later 1800's.
Keith Richards once said that upon the invention (or at least, last perfection) of the electric guitar in the early 1950's it was rendered complete, perfect, unimprovable.
One might say that of Canadian whisky - if one was a fan. I am, but only when it is at its best.