58 
SELECTED ARTICLES. 
of iron. The latter is suroxidated by the atmosphere, loses 
its carbonic acid, and passes to the state of the hydrated per- 
oxide. Now, in the pills prepared without addition, there is 
no mucilage to resist the action of the air and prevent the dis- 
engagement of carbonic acid; and both effects speedily take place. 
The pills become red on the succeeding day, swell and be- 
come powdery by handling. This state may still be remedied 
by rubbing the mass anew in a mortar, either alone or with a 
few drops of water, and re-forming the pills, which then are 
preserved in the air without any apparent new alteration. 
If, instead of making the pills without addition, it is desired 
to render them cohesive by means of gum tragacanth, the 
moment is seized when the mixture of the two salts appears 
to be complete, and half a drachm of pulverized gum traga- 
canth is added; if the mass be withdrawn when it begins to 
thicken, it hardens so rapidly that it is impossible to finish the 
pills before they become friable. It is better, therefore, to 
allow it to harden in the mortar, and to give to it the requi- 
site soft consistence with a little water, which is retained 
sufficiently long to make it into pills. 
If, instead of gum tragacanth, a drachm of gum arabic be 
employed, the mass assumes a good consistence, and may 
easily be rolled. But however favorable circumstances may 
be for the manipulation, it is rarely that it can be terminated 
as it is begun: the last made pills become dry and friable, and 
if a little water be added, the mass assumes an elastic mucila- 
genous consistence which opposes the formation of pills. 
By employing amidon instead of gum tragacanth, the mass 
instantaneously hardens, becomes friable, and cannot be 
moulded between the fingers. 
Powdered marsh mallows would be well calculated to give 
consistence to Blaud's pills, if it did not give rise to a par- 
ticular inconvenience arising from the nature of the substance. 
The mass remains soft and cohesive sufficiently long to divide 
into pills; but they exhale an ammoniacal and very disagreea- 
ble odor, produced by the reaction between the carbonate of 
