WOOD DISTILLATION. 
ACETONE. 
In the manufacture of acetone, calcium acetate is decomposed at a 
high temperature. . 
Ca (CH,COO), = CaCO, + (CH;),CO 
Calcium Acetate Acetone. 
The calcium acetate is placed in layers on shallow steel trays and 
introduced into suitable retorts heated by gas. At about 300 deg. C. 
decomposition takes place, and the evolyed vapours are condensed in | 
water-cooled coils. The distillate is not pure acetone, since numerous 
side reactions take place. Purification is effected by fractional distil- 
lation. ; ; 
When a very pure acetone is required, use 1s made of the ability 
of ketones to form sparingly soluble compounds with sodium bisulphite. 
CH, 
: CH,) « [OH 
cH CO + NaHSo, ={ sl qf 
CH,J ~ | NaSOy 
The crude acetone is mixed with a concentrated solution of sodium 
bisulphite, and after standing some time, crystals of the acetone bisul- 
phite compound separate out. These are filtered off, treated: with an’ 
alkali, and the product distilled in order to obtain a pure acetone. 
ForMALDEHYDE. 
Formaldehyde is a very important substance, and its uses are 
rapidly being increased. In the manufacture of dyes, it is employed 
largely in connexion with the triphenylmethane dyestuffs, such as 
magenta. It is used in the production of synthetic indigo. <A large 
number of artificial resins are produced by condensing formaldehyde 
with phenol and its homologues. The condensation product between 
resorcinol and formaldehyde serves to fix basie dyes in textile printing 
processes. With gelatine, formaldehyde forms an insoluble compound, 
and this is made use of in a well-known method for waterproofing 
textile fabrics. Moreover, it is generally well known that most direct 
dyes are made considerably faster by an after-treatment with a dilute — 
solution of formaldehyde. Finally, in the dyeing of cotton-wool unions 
with sulphur colours, a preliminary treatment of the wool with formal- 
dehyde helps to preserve it against tendering by the strongly alkaline 
dye liquor. Formaldehyde has a growing importance. 
When methyl alcohol is passed over suitable catalysts at a high 
temperature, partial oxidation takes place. Professor Bone has carried” 
out numerous researches in this connexion. By controlling the oxida- 
pee re possible to insure that a large proportion of formaldehyde is 
BeLOTMed 2) 
CH,OH + 0 = H.CHO + H, 
Methy! alcohol Formaldehyde. 
In the process of manufacture the catalyst usually consists of rolls 
of copper netting. Methyl alcohol is sprayed with hot air over the 
' catalyst which is maintained at a temperature of about 400 deg. C. 
The proportion of air to methyl alcohol must be carefully regulated. 
Air, of course, is the cheapest source of oxygen. But it is not possible 
€.19077.—5 689 : 
« 
