Page:Proceedings of the Royal Society of London Vol 4.djvu/143

Rh A paper was read, entitled, " Experiments made on a piece of Pena silver, saved from the Lady Charlotte, wrecked on the coast of Ireland in December 1838, as to its capability of holding water." By W. D. Haggard, Esq. Communicated by Sir Henry Ellis, K.H., F.R.S.

Plata Pena, so called, is silver collected by quicksilver after the ore is pounded ; it is then placed in a mould, and by great force the quicksilver is squeezed out, when it forms a mass, resembling dry mortar, of great porosity.

Troy Weight. Decrease lbs. oz. dwts. in weight.

Original weight when taken from the 1 oo m c\

j^jQ^ ° ^ 38 10 lbs. oz. dwts.

One day placed before the fire 37 15 1 9 5

TWrdday 35 5 1 7

Fifth day 34 5 5 11 15

Eighth day 34 2 5 3

Weight of water 4 9 3

Increase

Weight of the piece supposed to be 1 q ^ a o ^" weight,

qfitedry | 34 2 lbs. oz. dwts.

First day from the fire 34 3 1

Third day 34 2 5 2 2

Fifth dav 34 4 2 1 17

Eighthday 34 4 9 7

Gained in water from the air 4 7

Weight after water had been forced 1 39 i 19 4 9 10

into it J

Total weight of water contained in the piece 5 1 17

A paper was also read, entitled, " On the Application of the Con- version of Chlorates and Nitrates into Chlorides, and of Chlorides into Nitrates, to the determination of several equivalent numbers." By Frederick Penny, Esq. Communicated by H. Hennell, Esq. F.R.S.

The researches which form the subject of this paper were suggested by an inquiry into the most effectual method of ascertaining the quantity of nitrate of potassa existing in crude saltpetre. The author found that by the action of hydrochloric acid the nitrate of potassa was converted into the chloride of potassium; and conversely, that the chloride of potassium might, by the proper regulation of the temperature, be reconverted into the nitrate of potassa by the action of nitric acid. These mutual conversions afforded excellent means of determining, with great exactness, the relative equivalent numbers, in the theory of definite proportions, belonging to these salts, and to their respective constituent elements. The author, accordingly, pursued the investigation of these numbers by several successive steps, of which the details occupy the greater part of the present paper. He first determines the equivalent of chloride of potassium by decomposing chlorate of potassa into oxygen and chlo-