54 Scientific Intelligence. 
as assumed, by the drying up of extensive salt lakes. Again, 
aving confirmed the previous statements that the chief salt beds 
of the world are found on two geological somal the Lias and 
the middle Tertiary, he ah evidence t the aremma of 
beds—heated ‘it is ek b vetosnts aie —determines well- 
known chemical changes, from which result the peculiar acid va- 
pors there discharged. But we can only give here the barest out- 
boracic acid. rejects the test aco turmeric as menlarcirieyae 
in the presence of such a mass of salts as are found in bittern, an 
he finds the flame reaction by far the most sensitive as well as the 
most trustworthy of all the tests with which he has ri er aang 
When the Bunsen lamp is supplied with pure hydrogen, 
that the flame reaction will indicate the one-millionth of a gram of 
boracic acid. His method of applying the test is as follows: The 
material to be tested is first m with an excess of oil of vitriol, 
and this ea held in a loop of mpbichnrit wire is brought near— 
hin four millimeters—but never nearer than two millimeters 
to the visible mantle of the hydrogen se? so that the flame may 
not be colored in the least by sodium always present. If the 
assay contains boracic acid, th states green coloration 
appears, which can be identified with absolute certainty, by means 
of a spectroscope, and the coloration can be most delicately ob- 
served by looking through the mantle of the dame oo 
P 
6. Photo-electric Phenomena.—R. BornsTEIN enktiib es veins 8 ex- 
periments on the influence of light on the electrical tension in 
metals, and shows that the effect is not a thermo-electric one. 
The -Photo-electric series of the metals runs in this order :—Alu- 
minium, gold, copper, platinum, silver. While the thermo-electric 
series is as follows :—Silver, platinum, copper, gold, aluminium. 
His conclusions are as follows 
(1.) In a hee oma of 1 two different metals, a photo- 
electric current merated whenever the two junctions are ex- 
posed to arileeton jeaiacioms of different nro tee 
(2.) When the same junction is exposed in one case to an in- 
temperature, and in sauces to a more javeane illumina- 
