PHARMACY. 
tafes and expedites t!ie solution of some 
fixed principles, it gives olliers a tendency 
to decomposition, and dissipates all volatile 
matters. Decoction, therefore, can only be 
used with advantage for Uie extraction of 
principles which are neither volatilized nor 
altered by a boiling heat. 
To promote the action of the menstruum, 
infusion is sometimes premised to decoc- 
tion. 
In compound decoctions it is sometimes 
convenient not to put in all the ingredients 
from the first, but in succession, according 
to their hardness, and the difficulty with 
which their virtues are extracted ; and if 
any aromatic, or other substances contain- 
ing volatile principles, enter into the com- 
position, the boiling decoction is to be sim- 
ply poured upon them, and covered up un- 
til it cool. 
Decoctions should be made in vessels 
sufficiently large to prevent any risk of boil- 
ing over, and should be continued without 
interruption, and gently. 
The official preparations under this class 
are 
Decoctum althae® officinalis, Edin. de- 
coction of marshmallows. 
Decoctum antheraidis nobilis, Edin. de- 
coGtum chamemseli, Lond. decoction of cha- 
momile flowers. 
Decoctum cinchonae officinalis, Lond. 
Edin. decoction of Peruvian bark. 
Decoctum daphnes mezerei, Edin. de- 
coction of mezereon. 
Decoctum geoffrmaa inerinis,Edin. decoc- 
tion of cabbage- tree bark. 
Decoctum guaiaci officinalis comp. Edin. 
decoction of the woods. 
Decoctum helleborialbi, Lond. decoction 
of white hellebore. 
Decoctum hordei Lond. hord. disticlii, 
Edin. decoction of barley. 
Decoctum polygalas senegas, Edin. de- 
coction of seneka. 
Decoctum sarsaparillae, Lond. Dubl. de- 
coctum smilacis sarsaparillae, Edin. decoc- 
tion of sarsaparilla.- 
Decoctum smilacis sarsaparillae, Edin. 
decoctum smilacis sarsaparilla, comp. Dubl. 
Lond. decoction of compound i?f tliesarae. 
Decoctum ulmi, Lond. decoction of elm. 
Class XI. Infiisa. Infusions. 
We have already explained the sense in 
which we employ the term infusion. We 
confine it to the action of a menstruum, 
not assisted by ebullition, on any substance 
consisting of heterogeneous principles, some 
of which are soluble, and others insoluble, 
in that menstruum. The term is generally 
used in a more extensive, but, we are in- 
clined to think, a less correct sense. Thus, 
lime water and the mucilages, which are 
commonly classed with the infusions, are 
instances of simple solution, and the chalk 
mixture is tiie mechanical suspension of an 
insoluble substance. When the menstruum 
used is water, the solution is termed simply 
an infusion ; but when the menstruum is al- 
cohol, and upon a colouring material, it is 
called a tincture ; when wine or vinegar, a 
medicated wine or vinegar. Infusions in 
water are extremely apt to spoil, and are 
generally extemporaneous preparations. 
The following are those officially pre- 
scribed : 
Infusum cinchonse, Edin. infusion of Pe- 
ruvian bark. 
Infusum digitalis purpurea?, Edin. infu- 
sion of fox-glove. 
Infusum genlianae compositum Lond. in- 
fusiim gentiaua? lutea? comp. Edin. infusion 
of gentian, compound. 
Infusum mimosa? catechu, Edin. infusion 
of catechu. 
Infusum rhei palmati, Edin. infusion of 
rhubarb. 
Infusum ros-A, Lond. infusum rosse Gal- 
lica?, Edin. infusion of roses. 
Infusum sennae, Lond. Dubl. infusion of 
senna. 
Infusum senna?, tartarisatum, Lond. infu- 
sion of senna tartarised. 
Infusum tamarindi Ind. cum cassia senna, 
Edin. infusion of tamarinds and senna. 
Class XII. Muc'dagines. Mucilages. 
These, as officially prescribed, are as 
follow : 
Mucilago amyli Lond. Edin. mucilage of 
starch. 
Mucilago tragacanthae, Lond. ■ mucilago 
astragali tragac. Edin. mucilago gummi tra- 
gac. Dubl. mucilage of tragacanlli. 
Mucilago mimosae nilotic®, Edin. niuci- 
lago gummi arabici, Lond. mucilage of gum 
arable. 
Mucilago sera, cydonii mall, Lond. muci- 
lage of quince seed. 
Class XII. Syrupi. Syrups. 
In making these, the following is the pro- 
portion where no particulars are mentioned 
in respect to the weight of sugar. 
Take of double-refined sugar twenty-nine 
