gg BORAX LAKI, CALIFORNIA. 
the operations it had undergone, and a native zircon crystal, which on previous occasions 
Messrs Darker had occasionally ignited under the oxybydrogen blowpipe, is now as hard 
as ever having shown no tendency to crumble or soften dike lime beneath atmospheric 
influences. The heat had produced in it traces of vitrification, which could be seen only 
by the aid of a lens .—The Engineer. 
BORAX LAKE, CALIFORNIA. 
This sheet of water, the Lake “Kaysa” of the Indians is si T tu ? tea ,““® 2°" n & 
] 10 miles from San Francisco, and lies a little east of Clear Lake about halfi aj 
tween C&clie Creek Rnd H&wkin s v 1 * __ ±. 
This lake, which is separated from Clear Lake by a low range of hills belo ^ 1 °g 
the cretaceous period, has, under ordinary circumstances, a length of about a mde> and 
an average width of half a mile. Its extent, however, varies considerably at dfferent 
periods of the year, since its waters cover a larger area m spring than during the 
tumnal months. No stream of any kind flows into the basin, which fames its _supply 
of water from the drainage of the surrounding hills as well as, man ,^^ 
subterraneous springs discharging themselves into the bottom of thei lake In or dinary 
seasons the, depth, thus varies from 5 feet in the month of April, to 2 feet at the end o 
0 Bmax occurs in the form of crystals of various dimen:sions imbe<^ 
the bottom which is of an exceedingly unctuous character, and is found to be most pro 
ductive at a depth of about 3^ feet,’ although a bore-hole, which wui sunk near its centre 
to a depth of 60 feet, afforded a certain proportion of that salt thioughout its wh . 
The crystals thus occurring are most abundant near the centre of the lake, and this 
rich portion extends over an area equivalent to about obeAhird of a A ; 
are however, also met with in smaller quantities.m the muddy deposit of the other po„ 
tioA of the basin, some of them being, in the richest .part bef ore 
in weight The largest crystals are generally enclosed in a stiff blue clay, at a deptn o 
between 3 and 4 feet, and a short distance above them is a near y pure stratum of smaller 
ones, some inches in thickness, in addition to which crystals of various sizes are dis¬ 
seminated throughout the muddy deposit of which the bottom ,consists , , 
Besides the borax,thus found in a crystalline form the mud is lts f f h gbl J encl( f ed 
with that salt* and according to Oxland, when dried, affords (including the enclosed 
m-ystafs)17A3 per cent Anther sample, analysed by Mr. Moore, of Ian Francisco, 
afforded him 18 36 per cent, of crystallized borax. . - 
In addition to this the deposit at the bottom of the other portions of the basin, 
though less productive, still contains a large amount of borax, and it has been ascertained 
Taking numerous pits on the lake shore, that clay containing a certain portion of 
this salt exists in all the low grounds around it. .. rrv<;+als 0 t 
The borax at present manufactured is exclusively prepared from the native■ «y^ot 
crude salt whilst the mud in which they are found is returned to the lake, after the me 
chanical separation of the crystals by washing. The extraction of mud from the bottom 
is effected by the aid of sheet-iron coffer-dams, and dredging machines worked by manual 
power, the whole of the labourers being Chinese. Until 1866 the only ™ em¬ 
ployed consisted of a raft covered by a shingled roof, with an aperture in its centre, 
about 15 feet square, and above which were hung, by suitable tackle, four iron coffer¬ 
dams each 6 feet square and 9 feet in depth. This raft or barge was moved in parallel 
lines across the surface of the lake, and at each station the four damsTiTtLeThadThus 
taneously by their own weight into the mud forming the bottom. When they had thus 
become weU imbedded, the water was baled out, and the mud removed in buckets to 
We rectangular washing-vats, into which a continuous stream of water was introduced 
from the lake by means of Chinese pumps, the contents of the cisterns being at the same 
tl ^t C the t preseM^ 1 tiine^dredghi^-machines are employed for bringing up the mud and 
crystals from the bottom of the lake, and these are introduced into cisterns and washed 
a bove described. In this way the turbid water continually flows off, and a ceitam 
