24<fc> Mr . Home’s Observations on the Structure of 
been previously removed by disease. This uncommon appear- 
ance, at the time, could not be accounted for; but the fore- 
mentioned observations, on the formation of the enamel of the 
teeth, appeared to throw some light upon it; and Mr. Hatchett, 
at my request, made the following experiment, to determine 
whether the synovia, in a healthy state, contains phosphate of 
lime. 
960 Grains of synovia, by a gradual evaporation, afforded 21 
grains of a substance which resembled dried glue. This, being 
collected, was put into a small porcelain crucible, which (placed 
in a larger crucible) was exposed to a red heat, during nearly 
an hour. 
The matter in the porcelain crucible was much reduced in 
bulk, and appeared like a glazing, thinly spread on those 
parts of the crucible which had been in contact with it in its 
former state. 
Boiling distilled water was digested on the matter in the cru- 
cible, for some time. This water afterwards afforded, with ace- 
tite of lead, a copious precipitate of phosphate of lead ; but no 
appearance of lime could be obtained. 
On the residuum in the crucible, acetous acid was digested, 
which was afterwards divided into two portions. 
To one of these, solution of acetite of lead was added, and, as 
before, afforded a plentiful precipitation of phosphate of lead. 
To the other portion was added oxalic acid, by which, a small 
quantity of a precipitate was obtained, which was an oxalate of 
lime. Phosphate of lime is therefore present in synovia, although 
but in a small quantity ; and as, from these experiments, there 
is reason to believe, that more phosphoric acid was obtained 
