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Page:Popular Science Monthly Volume 21.djvu/368

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356
THE POPULAR SCIENCE MONTHLY.

account for the commencement of crystallization, which, so far as we can judge, must have been in an exceedingly weak solution. Nor does it perhaps seem possible that such complete seclusion from ascending and descending currents could in any way be secured. The winter rains pour in quite fierce torrents of drainage-water from all sides, often rendering the entire lake decidedly turbid, and of course causing more or less of commotion in every part. And in addition to this is the diffusion of particles, caused by the changes of temperature throughout the year.

In whatever light, therefore, the question is viewed, it is not free from difficulties. And yet at the same time it is but right to recall the fact that these green crystals are in their nature tincal, though such tincal as has never been found elsewhere, and that the crystals of tincal are perhaps in other localities formed subject to the same conditions as here prevail.

We turn now to Hachinhama, the other locality mentioned, as affording the borax-supply of California. This is on the southern side of Clear Lake, about four miles west of Borax Lake, which it closely resembles in its features, though much smaller, being an oval lagoon about four hundred yards in length. We have, as there, a sheet of clear alkaline-water, with a bottom of soft, plastic mud. This mud has been bored to about the same depth as in the explorations at Borax Lake, without its lower limit being reached.

The evidences that the alkaline pool occupies the space of an extinct crater, are more manifest here than at Borax Lake, as the inclosing walls still remain, though abraded on their northern extremity, while on the south they rise abruptly to the great mountain-summit of Conoktai.

The water of Hachinhama holds in solution the salts of soda in the following proportions: Sodium carbonate, ·754; sodium chloride, ·083; sodium biborate, ·163. The mud throughout its entire depth is richly stored with the same salts, but without any development whatever of crystallization of any kind.

After the cessation of work at Borax Lake, in 1868, attention was turned to the resources of Hachinhama. Of course, the style of working must be totally different, for here was no borax ready formed, no green crystals needing simply solution and recrystallization. All that was available was a sheet of water, holding the salts above recorded. The problem, then, was to separate in purity the borax—the only one of sufficient value to be worth the effort—and leave the others.

Borax being the least soluble of the three salts, and at the same time much more soluble in hot water than in cold, it was argued that, were the water of Hachinhama sufficiently concentrated by boiling and then allowed to cool slowly, the borax would crystallize out, leaving the carbonate and chloride in solution.

This is correct in theory, and in laboratory practice the results