344 J. Henry on the Construction of Laghtning-rods. 
chloride-ethylen salt and the iridium chloride-ethylen salt given 
above. 
The results were— 
‘1322 grms. dried at 100°: 
gave 0609 grms. metallic iridium = 46°07 pr. ct. 
1715 ere. dried at 1 
‘0784 grms. Ses iridium = 46°95 pr. ct. 
el, ( (C,H (NH, Cl) + H,O gives Ir. = 53°61 pr. ct. 
IrCl, (Cl, H,), (N NH ,Cl), gives Ir. = 39°25 pr. ct. 
The existence of the base iL TU EL). 
I ae to settle definitely by renewed analyses of larger 
quantit 
While engaged with the preparation of the ethylen and 
iridium compound, the thought of the possibility of acetylen 
(C,H,) ‘uniting with PtCl, or IrCl, led me to make some 
experiments in that direction. After 2 number of endeavors to 
form a platinum salt and analyses of the abate (a detailed 
account of which is given in the original paper), I obtained : 
negative results only. The existence of such a salt is highly = 
improbable. 
Art. XLV.—Directions for Constructing Lightning-Rods. From 
Essays on Meteorology; by Prof. JosspH HENRY.” 
to very combustible eae 
et fire to 
ed. It “Te should be, through its whole length, in aptiret ol 
continuity; as many pieces should be joined together by yee 
ing as practicable, and, when other joinings are unavoidab 6 me 
they sig aes be made b screwing the parts firmly pe. y cae 
a coupling ing taken to make the upper ©? 
tion hy ae tase stony with the rod water-tight by cement, solder, 
pai | 
3d. To secure it ee rust, the rod should be covered win ae 
cite of black pain . 
1S ee 
