THE DRYING FURNACE DI'.SCRIBED. 
a gentle heat evaporated to a mass, which while 
warm, should possess the consistence of thick 
tnrpentine, and after cooling should not stick 
to the fingers, but should rather crumble down 
when pressed. Considerable care is necessary 
towards the end of this process. When the 
solution is beginning to become thick it must 
be stirred with a curved iron spatula, of such 
a length, that it may extend over tlie whole 
vessel, in order to prevent the salt mass from 
being burned. 
The acetate of lime now half dry, is transfer- 
red from the evaporating vessel to a stone or 
iron plate, and spread hy means of the spatula 
to the depth of 2 or 3 inches, for the purpose 
of cooling. It should not remain so long as 
to attract much moisture, but shouhl speedily 
be subjected to the ^last operation, the drying 
end roasting ofthesalt. 
The drying furnace is a simple wind fur- 
nace, 7 or 8 feet long, 4^ to 5 feet broad, built 
of brick : at 6 inches above the ground is the 
ash pit. 8 inches broad and 12 inches high, 
which is covered with a grate of bricks. The 
fire-place is 20 inches high and 10 inches broad 
at the grate ; over it is an arch of bricks, so that 
the fire cannot play on and heat very highly, 
the iron drying plate lying on the side of the 
hearth. The space below the drying plate is 
separated from the hearth, by a partition of 
bricksSor 4inches high ; i2inche3 above tlie 
outlet of the earth there is a layer of iron bars 
to 2 feet from each other, ami noon these is 
deposited the drying plate. This consists of 
cast-iron ^of an iricli thick, and is formed 
according to the size oi the furnace. Round 
the plate tlie furnace is built up to the lieight 
of 10 inches, on tiie side of the front wall, 
leaving room for doors, which may be calcu 
lated at 2^ feet, d'hese doors are two, one 
above the other, through which the whole 
interior of tlie furnace can be inspected. 
They are formed of [ late-iron, and have in 
their middle a sliding door to admit of the 
exit of the vapour from the acetate of lime 
and of some ventilation. A wall built at the 
eud of the plate or a clay partition separates 
the whole of the drying plate from the chimney. 
In the walls of the furnace, iron-bars are fixed, 
and upon these lies a second drying plate 
which covers the drying space. 'I'his plate 
as it does not come in contact with the 
fire may consist of good iron or of clay. 
Above this drying space another is iormed 
by means of the chimney. "The heat passes 
aswellunder as above the drying space, and 
passes into the chimney, which is situated at 
the side of the furnace, and can be shut by a 
valve. In the drying space the temperature 
is nsnallv between 60® and 90® R. (167® to 
234^0 F.') 
Turf forms the best material for fue), as it 
does not burn rapidly, and produces a steany 
and equal temperature. 
DRYING OF IHE ACETAIE OF 
LI ME.-' When the furnace is tiiorongiily and 
equally heated, the flame of the fire is allovAed 
to subside. If wood is employed as fuel, the 
sliding door should be opened at the com- 
mencement, in order to allow' the. moisture to 
escape. The salt is transfened fiomthe eva- 
porating vessel to the drying plate, and spread 
out to the depth of two inches; and, after the 
first portion has become somewhat dry, the 
depth is increased to four or five inches; the 
heat is preserved at the degree already mention- 
ed for twenty-four hours, and during (his time 
tile salt is turned several times. Snhseqnently. 
when the mass appears to be becoming dry, 
the temperature niay be increased to 100® 
(257‘F.) so as to dry it completely. The mass 
is dry and properly roasted when it possesses 
the following char.acters ; It must, before cool- 
ing, be brittle, easily crumbled between tlio 
fingers, mixed with blackish carbonaceoua 
points or streaks, between which appear white 
pieces of dry salt, a solution of (he comminu- 
ted salt; in four or six times its volume of hot 
water possesses a yellowish brow n colour wdth 
a dark tinge, while previously it had a reiidish 
brow n colour. 
When the beat is increased tow’ards the 
end ol the process, as described, c.ire must be 
taken to do it gradually, so that no smoke shall 
rise from the acetate, because it might thus 
be decompo-ed. Neither must any spark be 
permitted to come in contact with the acetate 
of lime ; because, like sugar of lead, it pos- 
sesses the property, in these circumstances, 
of catching fiie and burning, by which the 
whole dry pieparaiion would be completely 
destroyed. The treatment of the acetate of 
lime in this manner, by means of gradual 
drying, as fx[;erience has shewn, possesses 
many advantages over the method of dry ing 
the salt in an open ve.«sel, becau.ve there is no 
loss of acetic acid, as always occurs by the lat- 
ter process. The operator has the {r eparation 
completely in his power, and with little ex- 
pense of fuel and time, many hundred w eights 
of salt can he prepared at once. 
This process does not merely extend the re- 
moval of the moisture from the acetate of lime, 
but a chemical influence is exerted by means 
of it. IBecause, it is certain that the sub- 
stances formed by dry distillation, which have 
been recently distinguished by Reichenhach, 
are partly dissipated by the heat, and partly 
decomposed; tlie acetate of lime possessing 
very different pro[!erlies before ami alter tlie 
pio'cess. After the i rocess the salt does nut 
imbibe waterso leadily as it did previously. 
After solution, filtraiion and evaporation, a 
much { urer product is obtained than betore, 
and upon the filter a resinous matter remains, 
the constituents of which have not yet beenex- 
amintd. After tlie completion of the previous 
steps the operator [ roceeds to the next, the 
SEPARATION OF PURE PYROLIG- 
NEOUS AND ACPYITC ACID.-Intoa cast 
irou lelort, cap able ol’ holding 30 measures of 
water, (of 2 lbs. Vienna weight), introduce 
20 lbs. (Vienna weight) of dry acetate of lime, 
and then 5 lbs. of water, and stir the mixture 
vvellnpby means of a wooden spatula. This 
preparation should be made in the evening, 
and the mixture allow ed to stand till the mom- 
in^. On the following day 20 ibs, of Engli^h 
sulphuric acid, diluted with 5 lbs. of water 
sliould be added, and the cover of tlie retort 
cemented. 
