Treating port with concrete in the 1840s

[AW77]

I just came across this book today: Smeed, T., The wine merchant's manual : a treatise on the fining, preparation of finings, and general management of wines, London 1845.

There is also a chapter on port in which the author recommends treating harsh port with "marine concrete" to make it less harsh (see the quote below). I wonder what this "marine" concrete is: a thickening agent made from fish meal ? I guess it's not the building concrete used in underwater (i.e. maritime) buildings.

Does anyone have a clue? It's probably easy for native speakers of English.
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"But, as regards the inferior quality of port wines, you must pursue a different course. If you happen to have a pipe of port that is either coarse, harsh, or unpleasant in its flavour, it becomes prudent to eradicate such defects as far as possible before you blend or make any use of such a wine. Now, to remedy these defects, you cannot possibly adopt any better mode than that of using the marine concrete, as recommended for
white wines. A coarse or harsh pipe of port will require a pound and a half of concrete; mix the concrete with about two gallons of the wine, and stir the whole well together before you pour it into the cask; then rummage it well about with your rousing stick, and afterwards you may fine the wine with the whites of fourteen or fifteen eggs, as you would have done had you not used the concrete. Or if it be convenient, it will be as well to fine the wine with eggs the day after using the concrete. For a hogshead or quarter cask, you will have of course to reduce the proportions accordingly. You may find thewine linger for a week or ten days in a dullish state, after being thus treated; but soon after it is racked you will discover a material improvement. Another important advantage has been proved to be derivable from this system of treatment, namely, that the crust of port wines thus treated generally adheres firmly to the bottle. This arises from the influence of the concrete in the neutralization of the peculiar tartarous qualities of these wines, which are well known to differ from most other description of wines."

http://babel.hathitrust.org/cgi/pt?num= ... 4088988886
P. 73 and 74

[griff]

I am suspecting bentonite. A quick google search supports prior use as a cement or support in marine situations.

[AW77]

Thanks. It probably is betonite. Besides, "concret" translates to "Beton" in some languages such as French, Dutch or German. So this Smeed might have translated it to make it sound more familiar to the readers of his manual.