TRANSACTIONS OF THE SECTIONS. 37 
zine is formed, but gases are immediately disengaged if distillation is attempted. 
Bichloride of titanium and stannic diethyl result in the reduction of the bichloride 
to the condition of sesquichloride, whilst the oily chloride of stannic sesquiethyl 
separates according to the equation 
Et Cl Et 
Sn Ti 7 Cl Sn 
Et Cr=2 40 Cle Ht 1.0, H, CL 
ssp (Ta (MO sng 
The paper concluded with considerations upon the possibility of substituting 
ethyl for oxygen in the organo-metals, and also remarked upon the question, pos~ 
sessed of considerable interest, how far, and in what manner, the introduction of 
different metals can be effected in the organo-metallic radicals, represented by the 
type 
X+ 
File 
X+ 
R/xt 
Can RR be represented by different metals, in the same manner as X may re~ 
present different alcohol radicals? The author hoped shortly to be in a position 
to answer this inquiry. 
On the Action of Nitric Acid upon Pyrophosphate of Magnesia. 
By Dueatp Campsett, Analytical Chemist to the Brompton Hospital, London. 
When pyrophosphate of magnesia was dissolved in ordinary nitric acid, and ex- 
posed in an open capsule to temperatures ranging from 320° F. to 550° F, till the 
weight became constant for each temperature, it was invariably found to have in- 
ee very much in weight; although not always to the same extent, as shown 
elow :— 
Temperature. Percentage increase of weight. - Difference. 
320° F. 
22 to 30 8 per cent. 
420 19 - to 21 a ea, 
550 135 to 14:5 ilar 
When the pyrophosphate of magnesia, still retaining nitric acid, but constant in 
weight at 320° F., was heated sufficiently to drive off all the nitric acid, it was found 
to have decreased in weight, not to a uniform amount, but varying from 9 to 16 
he cent., according to the greater or less rapid application of heat; on heating in 
he same manner the pyrophosphates of magnesia retaining nitric acid, and constant 
in weight at 430° F. and 550° F., they were found likewise to have decreased much 
in weight, although not to so great an extent, by pyrophosphate of magnesia being 
volatilized along with the nitric acid. 
It is inferred from these experiments that nitric acid has a stronger affinity for 
magnesia than pyrophosphoric acid has, and that on adding nitric acid to pyrophos- 
phate of magnesia, nitrate of magnesia is formed, pyrophosphoric acid being libe-~ 
rated; and this was proved to be the case by dissolving pyrophosphate of magnesia 
in nitric acid, evaporating the solution till syrupy, and then placing it under a 
bell-jar over sulphuric acid; after a time nitrate of magnesia crystallized, and 
pyrophosphoric acid could be drained off. 
But although nitrate of magnesia is formed and pyrophosphoric acid set free on 
the addition of nitric acid to pyrophosphate, it is probable that, when this mixture 
is evaporated and heated, the products are not always mere mixtures of nitrate of 
magnesia and pyrophosphoric acid, but that they are sometimes compounds; and 
the reasons for this opinion are, that these products are but slightly deliquescent, 
that ‘nitric acid is less readily expelled from them than from nitrate of magnesia, 
and that on heating these products suddenly, pyrophosphate of magnesia is yolati- 
lized, though it is not under ordinary circumstances a volatilizable salt. 
From the above results, the author recommends the discontinuance of moistening 
the pyrophosphate with nitric acid when calcining it, when estimating phosphoric 
acid or magnesia, as it may be apt to lead to a source of error. 
