48 
MANUFACTURE OF WOOD-NAPHTHA. 
pipe placed within the stills, or to the outside of the still, the lower 
half of which has been previously cased in an iron jacket. The 
pyroxylic spirit thus obtained is perfectly colourless, and is to be 
met with in the market of specific gravity varying from 0.870 to 
0.8320. 
The quantity as well as the quality of the pyroxylic spirit ob- 
tained at one works often differs much from that obtained at an- 
other works ; the kind of wood employed has something to do with 
this, but management of the process much more. The quantity 
varies from 1J gallon to 2| or even three gallons per ton of wood 
employed. 
The following Table was constructed by Dr. Ure, with the view 
of showing the per centage of real spirit in pyroxylic spirit of 
different specific gravities. The wood spirit employed in the con- 
struction of this Table was purified by distillation over powdered 
quicklime, and was drawn over with the heat of a water-bath at 
such a temperature that its specific gravity was 0.8136 at a tem- 
perature of 60° Fahr. 
Specific 
Gravity 
Real Spirit 
per Cent. 
Over Excise 
Proof. 
Specific 
Gravity. 
Real Spirit 
per Cent. 
Over or 
under proof. 
.8136 
100.00 
.9032 
68.50 
13.10 
.8216 
98.00 
64.10 
.9060 
67.56 
11.40 
.8256 
96.11 
61.10 
.9070 
66.66 
9.30 
.8320 
94.34 
58.00 
.9116 
65.00 
7.10 
.8384 
92.22 
55 50 
.9154 
63.30 
4.20 
.8418 
90.90 
52.50 
.9184 
61.73 
2.10 
.8470 
89.30 
49.70 
underproof 
.8514 
87.72 
47.40 
.9218 
60.24 
0.60 
.8564 
86.20 
44.60 
.9242 
58.82 
2.50 
.8596 
84.75 
42.20 
.9266 
57.73 
4.00 
.8642 
83.33 
39.90 
.9296 
56.18 
7.00 
.8674 
82.00 
37.10 
.9344 
53.70 
11.00 
.8712 
80.64 
35.00 
.9386 
51.54 
15.30 
.8742 
79.36 
32.70 
.9414 
50.00 
17.80 
.8784 
78.13 
30.00 
.9448 
47.62 
20.80 
.8820 
77.00 
27.90 
.9484 
46.00 
25.10 
.8842 
75.76 
26.00 
.9518 
43.48 
28.80 
.8876 
74.63 
24.30 
.9540 
41.66 
31.90 
.8918 
73.53 
22.20 
.9564 
40.00 
34.20 
.8930 
72.46 
20.60 
.9584 
38.46 
35.60 
.8950 
71.43 
18 30 
.9600 
37.11 
38.10 
.8984 
70.42 
16.60 
.9620 
35.71 
40.60 
.9008 
69.44 
15.30 
