[ 3»7 J 
If then they really be not globular but flat, and 
if water fo readily alter their fhape, whence is it 
that the ferum has the property of preferving them 
in that form which feems fo neceffary, becaufe it is 
fo general through the animal creation ? 
It is principally by the falts of the ferum that 
this effect is produced, as is proved by adding a 
fmall quantity of any neutral fait to water, when 
the water is no longer capable of diffolving thofe 
particles, nor does it alter their fhape when the fait 
is ufed in a certain proportion. 
Experiment III. If a faturated folution of any 
of the common neutral falts be mixed with frefh 
blood, and the globules (as they have been called, 
but which for the future I (hall call flat veficles) be 
then examined in a microfcope, the fait will be 
found to have contracted or fhriveled the veficles, 
fo that they appear quite folid, the vehicular fub- 
ftance being clofely applied all round the central 
piece. In proportion as the folution of fait is di- 
luted with water, it has lefs effeCt ; and, when di- 
luted with fix, eight, ten, or twelve times its quan- 
tity of water, it produces no change in the figure 
of the veficles, whofe flat fhape can then be feen 
even more diftindlly than when mixed with ferum 
itfelf. 
The neutral falts, which, when diluted with wa- 
ter, have been obferved to have the effefts above - 
defcribed, are Glauber’s fait, Epfom fait, a fait 
formed of the volatile alkali and the vitriolic acid, 
common nitre, cubic nitre, a fait made with the 
volatile alkali and the nitrous acid, as well as the 
falts made with the nitrous acid and magnefia, or 
T t a with 
