40 REPORT—1849. 
by Dr. Percy has not previously been formed. It is a remarkable fact, that the pre- 
sence of so large a quantity of phosphorus and iron should so little affect the tenacity 
and malleability of the copper. The effect also of phosphorus in causing soundness 
in the casting of copper is interesting, and may be of practical importance. Some 
experiments were next described, made by Capt. James of Portsmouth, bearing on 
the ceconomic value of the alloy of phosphorus and copper. By the experiments made 
by Capt. James on the corrosive action of sea-water, it would appear that this com- 
pound was much less affected than most other specimens of copper tried. The re- 
sults derived from exposing measured pieces of copper to the action of sea-water for 
nine months were as follows :— 
grains, 
Electrotype copper, loss per square inch .......... 1:4 
Selected copper ....--...0++ seed peh dave seaeed acer 
Copper containing phosphorus .....6..sseceeereeeee 0 
Copper from the “ Frolic” .........ssccccesesseceeeee 1°12 
Deckyard copper, No. I ...cessscsseeceesseesereeeeees 1°66 
Ditto INOiei, ctecties Ursa teas dak? Gants . 3:00 
Ditto INO(Aiessacdes cgedent denets dovewes come ae 
Ditto NO. 4 v.sesesssceresecsesseetsessres 23S 
Miantz/spmetalie.ce poeecsesudsecse «vonstune aide dante sec OD 
The results appear to be of sufficient importance to excite attention to the fact, and 
to elicit further inquiry, especially when it is remembered how important and ceco- 
nomic a desideratum it is to the Admiralty to diminish or prevent the corrosive effect 
of sea-water upon copper. 
On the Decomposition and partial Solution of Minerals, Rocks, &c. by pure 
Water and Water charged with Carbonic Acid. By Prof. W. B. Rocers and | 
Prof. R. E. Rogsrs, of the University of Virginia. 
In opening this communication, Prof. W. B. Rogers adverted to its important bear- 
ings upon the chemistry of geology, and the theories of the formation of soils and of 
the nutrition of plants. He referred to the comparatively isolated experiments of 
Struvé, Forchhammer and others, as being of tuo restricted a scope to furnish a basis 
for reasoning generally on the disintegration of rocks, the formation of chalcedonic, 
zeolitic and other minerals by solution, and the conveyance of inorganic materials 
into the structure of plants, It therefore becomes a question of importance, whether 
water pure, or charged with carbonic acid, possesses that general decomposing and 
dissolving power which some chemists have vaguely and without sufficient evidence 
ascribed to it, or whether this action applies only to the few materials hitherto tried, 
and which all contain an alkali. ‘ 
The experiments of the Professors Rogers were of two kinds; first, by an extempora- 
neous method with the tache ; atid secondly, by prolonged digestion at the ordinary tem- 
perature. In the former, a small quantity of the mineral in very fine powder is di- 
gested for a few moments on a small filter of purified paper, and a single clear drop 
of the liquid received on a platinum slip is dried and examined by appropriate tests 
before and after ignition. In the second process a quantity of the finely-powdered 
mineral is placed with the liquid in a green glass bottle and agitated from time to 
time for a prescribed period. ‘The liquid separated by filtration is evaporated to dry- 
ness inaplatinum capsule. The residuum is then critically examined, and, if in suf- 
ficient amount, is submitted to quantitative analysis. 
In both processes two parallel experiments were made, the one with pure aérated 
water, the other with water charged to saturation at 60° with carbonic acid. In the 
second process, correction was made for the alkali, lime, &c. dissolved from the con- 
taining glass, by making separate experiments in similar vessels without the mineral 
powders. 
1. When the substance is very minutely powdered before mingling it with the 
liquid, even the first drops that pass the filter will commonly give a tache containing 
some of the alkali or alkaline earth that has been dissolved. In this way proof of 
the action of the carbonated water may generally be obtained in a few minutes after 
adding it to the powder. In the case of pure water the action is feebler and requires 


