131 
dioxide in such quantity that it would suffice to convert 
all the sodium present into sodium hydric sulphite. How- 
ever, alcohol separates sodium dihydric phosphate from the 
solution, and less than fths of the sulphur dioxide are expelled 
by boiling-. The concentrated solution obtained by satu- 
rating the crystals with the gas, shows the peculiar pheno- 
menon of separating into two distinct liquids by gravitation; 
agitation unites these again to a perfectly homogeneous 
liquid. 
2. Sulphur dioxide in aqueous solution has no action 
upon bismuth-, stannous-, stannic-, and metastannic- phos- 
phate. 
3. Sulphur dioxide and water act upon some phosphates 
in the same manner as other strong acids by forming a sul- 
phite and phosphoric acid. The phosphates of barium, 
silver and lead have been observed to undergo this decom- 
position. 
4. Calcium arsenite, calcium arseniate, and cupric vana- 
date are dissolved like the first group of phosphates, 
without decomposition by sulphur dioxide and water. 
The solution of the first forms calcium sulphite by boiling, 
the second begins soon to deposit calcium sulphate, owing 
to the reaction of arsenic acid on sulphurous acid, and the 
solution of the vanadate on boiling deposits beautiful 
golden colored scales, which are, probably, copper vanadite 
sulphite. 
5. Calcium oxalate is dissolved, in very minute quantity, 
by water charged with sulphur dioxide, and is deposited 
unchanged after expulsion of the gas. 
*** This paper was read at the Meeting of the Society, 
held on the 21st February, 1871. 
“ Further Observations on the Strength of Garden Nails,” 
by J. P. Joule, LL.D., F.R.S., Y.P. 
The author thought it desirable to ascertain how far 
