A F F

A FF

( 13 )

since 99.548 would be the quantity of this the direct oxygenation of a super-sulphuret ofperoxyd that contains oxygen equal to half the copper, this would of course contain a doublesulphur in the acid. proportion of sulphur, and its proportions when

Lastly, if this latter sulphat were formed by resolved would be as follows:

Oxygen.

Copper - 100.0 with 25.60 give 125.60 peroxyd of copper

Sulphur - 51.2 74.97 126.17 sulphuric acid

Super-sulphuret 151.2 100.57 251.77 Sulphated Peroxyd of CojSper

The author then proceeds to examine theaccuracy of these hypothetical numbers byactual experiment. We shall state them in avery few words.

The peroxyd of copper was formed byevaporating and igniting a given weight ofmetal dissolved in nitric acid. Another portionof the nitrat was decomposed by a carbonatedalkali, and the precipitate ignited. In the formercase some of the metal was volatilized with theacid, and in the latter a portion was left inthe solution and separated by sulphuretted hy-drogen, both of which circumstances producesome little inaccuracy in the results. An al-lowance must also be made for the sulphur andcarbon retained by ail copper. If this be fixedat per cent, (which however is quite arbitrary)the composition of the peroxyd of copper willbe Copper 80 — 100

Oxygen 20 — 25

100 125

which very nearly agrees with the proportiondeduced from the sulphuret.

The suboxyd of copper was formed by mix-ing 10 parrs of the peroxyd with the samequantity of pure copper in a flask, containing75 parts of muriatic acid, and keeping thevessel well closed on a gentle stove-heat forthree days, with frequent shaking. After thisthe whole of the peroxyd and part of the cop-per were dissolved, and the quantity of thelatter was found by weighing the undissolvedportion. Then supposing the oxygen of theperoxyd to be equally divided between its ownportion of metal and that added, and the wholeto constitute the suboxyd, this will nearly con-tain half the oxygen of that in the peroxyd,allowing a small deviation to be produced bythe unavoidable action of the muriatic acid ona small portion of the copper, independently ofthe oxygen present, which was shewn by anescape of hydrogen when the vessel was opened.A suboxyd of copper containing half the oxy-gen of the peroxyd, will therefore consist of

Copper 88.89 — 100.0Oxygen 11.11 — 12.5

100 00 112.5

This very nearly agrees with the result ofa similar experiment made by Mr. Chenevix,who reckons 13. of oxygen to 100. of metal;and the composition of this suboxyd estimatedfrom the sulphuret is the mean of these two,or 12.8 of oxygen.

The common sulphat of copper was thenanalyzed : 5 parts of this salt dried at a tin-melting heat and decomposed by muriat ofbarytes, gave 7.22 of sulphat of barytes, theacid of which is 2.455, leaving therefore 2.545for the oxyd of copper in the 5 parts. Thebasis of this salt' is the peroxyd of copper,and therefore this salt is properly the sulphatedperoxyd of copper. It is thus composed, from,the above analysis:

Sulphuric acid 49.10 100.00

Peroxyd of copper 50.90 103.66

100.00 203.66

On the other hand, if 100 parts of sulphuricacid neutralize so much of any base as contains-20.29 parts of oxygen, it would require 101.45instead of 10 3.66 of the peroxyd.

The quantity of peroxyd saturating 100. ofsulphuric acid, as estimated by the compositionof the sulphuret, is 99.548, which is still suf-ficiently near 103.66 to come within the limitsof probable error.

The above experiments on the compoundsof copper with sulphur and oxygen are so fardefective that they do not exhibit any super-sulphuret of copper, which is the regular baseof the common sulphat of copper or sulphatedperoxyd : nor on the other hand do they shewany sulphated suboxyd of copper, which is theregular product of the oxydation of the subsul-phuret actually known. They sufficiently il-lustrate, however, the law of definite proportionsin the different degrees of oxydation ■, and that