Frankly, when I started investigating the mummified cats, I was hoping to debunk it. The story is usually told quite badly, with important details omitted or mangled, and exaggerated to the point of falsehood. The most common exageration is to use the Liverpool cat auction as a stand-in for the other importations of mummified cats that must have occurred, even though no one wrote down a word about them. I'm convinced that this was it.
Many, many thanks, by the way, to the indefatigable Obooki for the English newspaper articles supplied in comments here. His work is a tribute to the historic Anglo-American Special Relationship. The articles answer more questions than they raise, which is progress. For one thing, the seesawing tonnage of mummified cats is explained: there was one shipment (19 1/2 tons) and two auctions, half of the cats in the first, half in the second. The same buyer "won," if that's the right word, both lots, paying 1.6 times more for the second lot - all of that newspaper publicity must have driven up the price. That second auction sounds like a circus. A circus whose only attraction is cat mummies.
Bones as Fertilizer: 19th century England had an active animal bone and bone ash import trade that dates from the late 18th century and continued well into the 20th century. Bones were ground and directly applied to crops, or, as the chemical fertilizer industry developed, used to make superphosphate fertilizers. Although "15 per cent were taken by bone-turners and other for non-agricultural purposes."* I don't even want to know. Bone ash china, ma femme suggests. Good point.
The article that supplied that quote also has a handy table of fertilizer prices, 1840-1870, including nitrate of soda, Peruvian guano, and "half-inch bones." If I am reading the table correctly, the supposed mummy cats were auctioned for a price per ton comparable to that of other bone imports, at least in the first lot. But the bone price series is incomplete, so who knows if the cats were bought at a premium or a discount.
Did you know that almost all of the guano imported into England went onto turnip crops? Turnips and "swedes"? What the heck is a swede? (It's a rutabaga). All turned into animal feed.
My bone chemistry question: does the phosphate content of old bones change over time? Would four thousand year old animal bones be as useful for fertilizer as new ones? It's a mineral, so why not.
Mummy Paint, Mummy Powder: The thing that still puzzles me is that mummies were in fact imported to England for two high-end purposes. They were ground up to powder for sale as a) medicine, and b) paint. The scattered and poorly sourced references I've found to these trades refer to these as valuable items, priced per ounce, not per ton. But I have no idea what amount of actual mummy went into paint and quack powder. The medicinal mummy dust was notoriously faked. And anyway, the key part of mummy powder was a mineral salt called natron, which is part of the rags, not of the bones.
I haven't been able to figure out which part or how much of the mummy went into "Mummy Brown" or "Egyptian Brown" paint, either. I read a crazy story about the painter Lawrence Alma-Tadema coming upon his assistants grinding up a mummy for paint. Alma-Tadema, horrified to learn that there was human material in his paint, rushed off to tell Edward Burne-Jones, who also didn't know that "Mummy Brown" contained actual mummy. They then - well, let's turn to Rudyard Kipling's memoir. Burne-Jones was Kipling's uncle:
And once he descended in broad daylight with a tube of 'Mummy Brown' in his hand, saying that he had discovered it was made of dead Pharoahs and we must bury it accordingly. So we all went out and helped - according to the rites of Mizraim and Memphis, I hope - and - to this day I could drive a spade within a foot of where that tube lives. (Something of Myself, Chapter 1, p. 10 of the 1990 Cambridge University Press edition).
Note that Alma-Tadema has vanished from Kipling's version, which was written fifty years after the fact. Is any of this true? I thought art historians had gotten interested in materials and prices and that sort of thing, but I can't find any real information about "Mummy Brown."
Is this all the result of a large mummy trade? Or the product of a small number of mummies smuggled out of Egypt (I've seen sources that imply this)? Or is the amount of actual mummy rather more homeopathic? And why couldn't the cats be used for this more valuable purpose? You can order your own supply of mummy-free Mummy Brown right here.
How to read late 19th century newspapers: One thing I've learned here is that I don't really know how to use these sources. To what degree should I trust what I find in a late 19th century newspaper? Of all the newspaper articles I or Obooki found, only one (The Bristol Mercury and Daily Post, Feb 11, 1890) reads like an eyewitness account. Newspapers today have been known to print lightly edited press releases. They're a source; sources have problems; be careful out there.
Perhaps it's better that the mummified cat story is true. It's so ridiculous. So unrealistic. So much fun.
* All guano and bone-related information from Mathews, W. M. "Peru and the British Guano Market, 1840-1870." The Economic History Review, 23:1 (April 1970), pp. 112-28. That bone-turner business is from footnote 6, p. 121. The table with the price series for various types of fertilizer is on p. 120. Note that the period covered here ends before the legendary mummy cat auction.