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6. Radiant. Heat, (L’Institut, No.'629; Jan. 21, 1846, p- 
| Pp. 22.)—M. 
Knoblauch, of the Academy of Sciences of Berlin, has found by experi- 
ment, that the diathermal modifications. which heat undergoes by re- 
flexion differ according to the source of the heat; that (1) these modifi- 
cations are quite decided with heat from an argand lamp ; (2) they are 
much less for heat from incandescent platina; (8) they are still less for 
the heat from an alcoholic lamp; and that (4) none whatever can be 
distinguished for heat from a cylinder of iron heated between 68° and 
820° F. 
_ These modifications depend either on a transformation of the calo- 
rific rays, rendering them more or less transmissible across diathermal 
substances; or they result from an elective absorption by the reflecting 
surfaces, a view rendered probable by the experiments of Powell 
and Melloni. Experiment has shown that carmine facilitates the pas- 
sage of heat across cale spar. If this effect is owing to its absorbing 
those rays which traverse calc spar with difficulty, it ought to reflect as 
much less perfectly the heat from a source which affords those rays that 
traverse the spar with difficulty. Now, it is found that heat from. the 
cylinder of iron traverses cale spar much less completely than that from 
anargand lamp ; consequently carmine, in case of an elective absorption, 
ought to reflect the heat of the iron less perfectly than that of the lamp. 
This is fully confirmed by experiment. 
%. Milk of the Milk tree, (L’arbre de vaches, Galactodendrum utile.) 
—An analysis of this vegetable milk, afforded M. Heintz the following 
result: water 57:3, vegetable albumen 0-4, a species of wax (having 
the formula C35 H&S O8) 5:8, a resin soluble in cold or boiling alcohol 
(corresponding to the formula C** H®® O?) 31:4, gum and a kind of 
sugar 4°7, bases resisting the action of heat, such as magnesia, soda, 
traces of potash and lime combined with phosphoric acid, and an organic 
acid undetermined 0-4—100. This agrees nearly with the analyses of 
MM. Boussingault and Mariano; but differs so much from that by M. 
Marchand, that M. Heintz suspects he may have examined the milk of 
another species of plant. 
8. Artificial Asbestus, (Proceedings Phil. Soc. of Glasgow. )—A speci- 
men of this substance was found in a blast furnace, imbedded in the mass 
of matter which had collected at the bottom of the furnace, in the course 
of two years and a half. It was in a cavity about eight inches below 
the level on which the liquid metal rested, and was interspersed with 
beautiful crystals of titanium. It has the general character of asbestus, 
forming small masses, consisting of delicate filaments of fibres éasily 
separable. The fibres are flexible, though not so much so as common 
asbestus ; they fuse with difficulty, and are not attacked by sulphuric, 
nitric or muriatie acid. ' 
Sxrconp Sernies, Vol. I, No. 3.—May, 1846. 55 
