INDEX. 
page 
Platinum , properties of this peculiar compound of pla- 
tinum, , - - 110 
composition of this peculiar compound of pla- 
tinum, - - - - - ill 
— observations on this peculiar compound of pla- 
tinum, - - - - - 115 
Platinum , grey oxide of, observations on it, - 121 
properties and composition of it, 121 
Platinum, .sulphate of, its effects upon gelatine, - 118 
on the efficacy of this substance as a 
test for gelatine, - - - - 119 
Polarised rings, description of an instrument employed in 
experiments upon them, - - - 96 
Presents, a list of those made to the Royal Society, from 
November 1819 to July 1820, - 333 
Proteosaurus , on the mode of formation of the canal for 
containing the spinal marrow, and on the form of the 
fins (if they deserve that name) of this animal, - 159 
— — — the structure of its vertebras, - - 160 
R 
Raffles, Sir Thomas Stamford. Some account of the 
dugong, - - - - - 174 
Rochon, M. Extract of a paper of his in the Journal de 
Physique, relative to the construction of micrometers, 130 
Rock crystal, on the method of cutting it for micrometers, 126 
S 
Seppings, Sir Robert On a new principle of construct- 
ing ships in the mercantile navy, - - 133 
Ships, on a new method of constructing them in the mer- 
cantile navy, - - - - - 133 
Snow, red, some experiments on the fungi which constitute 
the colouring matter in that discovered in Baffin’s Bay, 165 
Snowdon , on the measurement of that mountain by the 
thermometrical barometer, - - 2 95 
Solstices, observations of those in the years 18 18 and 1819, 330 
observations of those in the years 1818 and 1819, 
computed by Mr. Groombridge’s table of refraction, 330 
Sounds, on those inaudible by certain ears, - - 306 
Stone, an account of a new mode of performing the high 
operation for that disease, - 209 
