In twenty-four hours, without any toxic symptoms. The artificial acid and its salt contain ortho-, paraand meta-cresotic acids, which are cardiac depressants.
The economic importance of salt is further indicated by the almost universal prevalence in ancient and medieval times, and indeed in most countries down to the present day, of salt taxes or of government monopolies, which have not often been directed, as they were in ancient Rome, to enable every one to procure so necessary a condiment at a moderate price.
The great similarity between the salts of the ocean and the gaseous products of volcanic eruptions at the present time, rich in chlorides and sulphates of all kinds, is a strong argument for the ocean having been salt from the beginning.
This is generally effected by adding the calculated amount of potassium chloride (of which immense quantities are obtained as a by-product in the Stassfurt salt industry) dissolved in hot water to a saturated boiling solution of sodium nitrate; the common salt, which separates on boiling down the solution, is removed from the hot solution, and on cooling the potassium nitrate crystallizes out and is separated and dried.
About a fourth of the salt produced is exported to foreign countries, and of this about three-fourths goes to British India.
Lead fluoride, PbF2, is a white powder obtained by precipitating a lead salt with a soluble fluoride; it is sparingly soluble in water but readily dissolves in hydrochloric and nitric acids.
The action of sandstone in filtering salt waters was investigated in 1878 by Dr Isaac Roberts, F.R.S., who showed that when salt water was allowed to percolate blocks of sandstone, the effluent was at first nearly fresh, the salt being filtered out and crystallized for the most part near the surface of ingress to the sandstone.
This salt may be prepared by digesting flowers of sulphur with sodium sulphite solution or by boiling sulphur with milk of lime.
Ignipalliatus, from Peru to Patagonia, more resembles the classical species; while P. andinus, the tallest of all, which lacks the hallux, inhabits the salt lakes of the elevated desert of Atacama, whence it extends into Chile and Argentina.
The mother liquors are concentrated, and the double salt of composition 2KF CbOF 3 H 2 O, which separates, is decomposed by sulphuric acid, or by continued boiling with water (C. Marignac; see also G.