OXALIC ACID. 
543 
§§ 7 I 7-72I.] 
and manganese salts, 1 and citrate of soda, and is also decomposed by boil¬ 
ing with solutions of copper, silver, lead, cadmium, zinc, nickel, cobalt, 
strontium, or barium salts. It is insoluble in solutions of chlorides of 
the alkalies and alkaline earths, and in water, in alkaline solutions, or 
in acetic acid ; and is soluble in mineral acid only when the acid is 
strong and in considerable excess. It is unalterable in the air, and 
at 100°. When carefully and slowly ignited it may be wholly con¬ 
verted into carbonate of lime ; if the heat is not properly managed 
(that is, if excessive), caustic lime may be formed in greater or smaller 
quantity. 
§ 717. Use in the Arts. —Oxalic acid is chiefly used by dyers and 
calico-printers, but also by curriers and harness-makers for cleaning 
leather, by marble masons for removing iron stains, by workers in 
straw for bleaching, and it is applied to various household purposes, 2 
such as the whitening of boards, the removing of iron-mould from linen, 
etc. The hydropotassic oxalate (binoxalate of potash), under the 
popular names of “ essential salt of lemons ” and salts of sorrel, is used 
for scouring metals and for removing ink-stains from linen. 
§ 718. Hydropotassic Oxalate, Binoxalate of Potash, KHC 2 0 4 (H 2 0), 
is a white salt, acid in reaction, soluble in water, and insoluble in alcohol. 
Heated on platinum foil it leaves potassic carbonate, which may be 
recognised by the usual tests. Its aqueous solution gives, with a 
solution of acetate or sulphate of lime, a precipitate of calcic oxalate 
insoluble in acetic acid. 
§ 719. Statistics. —Poisoning by oxalic acid is more frequent in 
England than in any other European country. In the five years ending 
December 1916 there were registered in England and Wales 448 oxalic 
acid deaths. Of these 37 (12 males and 25 females) were accidental, 
410 (222 males, 188 females) were suicidal, and there was one case of 
murder. Oxalic acid occupies about the second place among poisons, 
arranged in order of frequency. 
§ 720. Fatal Dose. —The smallest dose of oxalic acid known to have 
destroyed life is, according to Dr Taylor, 3-88 grms. (60 grains) ; but 
recovery has taken place, on prompt administration of remedies, after 
eight times this quantity has been swallowed. 
With regard to oxalate of soda, or binoxalate of potash, 14*2 grms. 
(half an ounce) have been taken without fatal result, although the 
symptoms were very serious ; and it may be held that about that quantity 
would usually cause death. Oxalic acid is not used in medicine, save as 
a salt, e.g. oxalate of cerium. 
§ 721. Effects of Oxalic Acid and Oxalates on Animals. —The first 
cases of poisoning by oxalic acid occurred early in the nineteenth 
1 But it is reprecipitated unaltered by excess of alkaline oxalate. 
2 A “ liquid blue,” used for laundry purposes, contains much free oxalic acid. 
