45 
molecular change called polymerization, whereby a solid form is 
obtained, known as paraformaldehyde or simply p>araform. When 
a solution of formaldehyde is evaporated by heat, and more slowly by 
long standing, paraformaldehyde separates as a white, flocculent, 
nearly odorless mass, which is almost insoluble in water, alcohol, or 
ether, and which begins to sublime below 100° C. When heated, 
paraformaldehyde vaporizes and reforms the gaseous formaldehyde. 
It occurs in the market in tablets which are employed for disinfecting 
purposes. 
Formaldehyde is very active chemically; it has a strong reducing 
action on silver, copper, and mercury salts, and unites readily with 
ammonia, forming the official odorless Hexamethylenamine (which 
see). It is easily oxidized by hydrogen dioxide and potassium per- 
manganate, especially in alkaline solution. 
Several dusting powders containing formaldehyde, in combination, 
have been introduced; thus, gluiol is a compound of gelatin and for- 
maldehyde, amyloform , of starch and formaldehyde, etc. 
Formaldehyde is a constituent of many food preservatives, embalm- 
ing preparations, etc. 
Caution. — Keep well stoppered in a moderately cool place and pro- 
tected from light. 
o 
LIQUOR SODII PHOSPKATIS COMPOSITES. 
Compound Solution of Sodium Phosphate. 
A fairly stable concentrated solution containing 1 Gm. of Sodium 
Phosphate in each Cc. 
Dose. — “Average dose: 8 Cc. (2 fluidrachms).” (U. S. P.) 
Keep well stoppered and moderately warm. 
MAGNESII SULPHAS EFFER VESCENS. 
Effervescent Magnesium Sulphate. 
A similar compound is official under the same name in the British 
Pharmacopoeia; known also as effervescent Epsom salt, and as magnesii 
sulphas granulatus. 
This may take the place of Magnesii Citras Effervescens (II. S. P., 
1890), which has been dropped. 
Dose. — “Average dose: 16 Gm. (240 grains).” (U. S. P.) 
MALTUM. 
Malt. 
This is a reintroduction; Maltum was official in the U. S. Pharma- 
copoeia, 1880, but was dropped in 1890. Used for the preparation of 
Extractum Malti (q. v.). 
