96 On the Decomposition of the Earths. [Jan, 
grains$ but we have obtained drops of metal weighing 14 grains 
when the current of gas is diminished so as not to let the metal run 
off too quickly from the wire. And by placing several globules 
upon a piece of charcoal, and suffering the whole force of the 
gas to act upon them, the metal is made to boil, and they all run 
together into one mass. In this manner, as a test of the heat, I 
have obtained a globule of platinum weighing 23 grains, which is 
now sent with others for your inspection. 
13. Semi-Metals.—A few words respecting the substance called 
semi-metals will now conclude these observations, The description 
given in works of chemistry is to a certain extent erroneous with 
regard to these bodies, their colour, lustre, and hardness. It is an 
error, for example, that most of them become rapidly ox:ded by 
exposure to atmospheric air. Of course my remarks must be re- 
stricted to those metals which do not become volatilized by the heat 
of the ignited gas. I shall describe some of them as they now ap- 
pear more than four months after their reduction to the metallic 
state. 
Cobalt is a metal somewhat darker than zron, easily admitting the 
action of a file. 
Manganese resembles the metal of barytes: and this you have 
also stated, as being your own opinion, respecting the latter. It is 
somewhat harder than cobalt; exhibiting a whiter colour, and a 
greater degree of lustre. 
Tungsten, or Scheelin.—This metal I obtained from wolfram. It 
resembles the magnetic iron ore of Lapland; not being, however, 
itself magnetic. Upon the action of the file it discloses a brilliant 
metallic surface with a high degree of lustre. 
Molyldenum, resembles arsenical iron; but when further re- 
duced, and exhibited in the form of globules, it has the whiteness 
of the purest szlver. 
Uranium, is the hardest of all the semz-metals. The sharpest 
file will scarcely touch it. ‘The colour and lustre of this metal re- 
semble those of polished iron. 
Titanium.—The exterior surface of this beautiful metal, after 
fusion, is of a black colour; like the metal of larytes, when ob- 
tained directly from the earth. It is very hard. When filed it is 
nearly as white as silver. 
Cerium.—The appearance of this metal is like that of won. It 
is very hard, and its surface after fusion is of a brownish colour. 
I cannot conclude a description of these results without once more 
congratulating your chemical and mineralogical readers upon the 
powerful means of analysis which are now offered to their use; and 
as we are at length enabled to conduct every experiment without the 
slightest danger to the operator, I trust it will not be long before 
other results, far exceeding in their importance any that I have been 
fortunate enough to obtain, will give additional interest, not only to 
your Annals, but also to the sciences, towards whose advancement 
your labours have so materially conduced. 
Cambridge, Dee, 4, 1916. Epwarp Danie CLARKE. 
