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A treatise on the manufactures and machinery of Great Britain / by Peter Barlow ; to which is prefixed An introductory view of the principles of manufactures by Charles Babbage : forming a portion of the Encyclopaedia Metropolitana
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436

MANUFACTURES.

Manufac- gluey, which it continues to be after exposure to the air,tures. The soap of which linseed oil forms a constituent part,iis at first white, but changes to yellow in a short timeby exposure to the air: it possesses a strong odour, isunctuous, clammy glutinous, does not dry in the air,and softens with a very small quantity of water.

From what has been said, we may conclude that thesoaps prepared with desiccative oils are of a very in-different quality, that they remain always glutinousand readily change their colour on exposure to the atmo-sphere.

(624.) The following are the quantities of hard and soft,soap charged with duties of Excise in the United King­ dom , and the net produce of the dutv in each year, from1820 to 1831.

Years.

Quantity of hardSoap chargedwith duty.

Quantity of softSoap chargedwith duty.

Net produce ofduty.

lbs.

lbs.

£.

1820

82,413,223

6,903,356

928,602

1821

87,717,693

7,470,030

1,023,534

1822

89,672,508

7,576,422

1,120,989

1823

87,071,456

8,226,922

1,147,660

1824

100,270,453

9,297,485

1,194,361

1825

102,623,165

8,910,504

1,199,364

1826

96,859,694

7,278,446

1,144,539

1827

104,371,285

9,646,477

1,230,663

1828

108,193,606

10,024,665

1,201,754

1829

103,041,941

9,068,918

1,151,906

1830

117,157,916

10,209,519

1,249,684

1831

108,956,030

9,641,907

1,138,262

Sulphur Works.

Sulphur (625.) Sulphur occurs native in many places narticularly in the Kingdom of Naples , and is frequently nearlym a state of purity, or slightly combined with earths. Thewhole preparation which it requires, therefore, in thiscase, to render it fit for the purposes of commerce, i 3 tofree it from its earths by distillation.

In other cases it is obtained artificially in the roastingof copper ore, as at the celebrated Paris mountain cop- ^per mine in the Island of Anglesea. There works tor obtaine d bythat purpose are constructed on a large scale. At the roas tingfoot of a low but a steep ridge of rock are constructed copper or® 1masses of masonry, not unlike high blast-furnaces, exceptthat the top is capped with a dome of brickwork, fromwhich proceeds a horizontal flue, about the size of acommon chimney, which terminates in a square or ob-long brick chamber, built at the top of the rock. Somelighted fuel is introduced by means of a door in thedome of this roasting furnace, and a few baskets full ofore, broken into moderately small pieces, are thrown on,fresh parcels of ore being added from time to time ; asthe preceding parcels get lighter, a sufficiency of air forthe slow combustion required in this process is let in bymeans of a door at the bottom of the kiln, which alsoserves for taking out the ore when properly roasted; thepart of the sulphur which escapes combustion rises invapour, and collects in the dome, (the door of which isonly opened to admit fresh charges of ore,) whence itpasses through the flue into the chamber, where it pre-sently concretes, lining the sides and roof; each chamberhas a door, by means of which, about once in six weeks,it is cleared of the sulphur. This rough sulphur is inspongy, pulverulent crusts, of a dirty greyish-yellowcolour. For its purification it is melted in a boiler, theimpurities are got rid of by skimming and subsidence,and the fluid mass is then laded into cylindrical mouldsto form the common roll sulphur or brimstone, or intocones about two feet high, forming the loaves of sul-phur. The impure dregs are also sold in the shopsunder the name of sulphur vivum. The sulphur which isprocured in the roasting of ores, especially those of cop -per, is apt to contain, besides earthy impurities, a veryconsiderable proportion of arsenic, while, on the otherhand, the volcanic sulphur in general, and that of Sicily in particular, is entirely free from this contamination;which is the cause of the universal preference given by themanufacturers of sulphuric acid to Sicilian over English sulphur.

(626.) Table, showing the Quantities of Brimstone imported and exported from the United Kingdom , and cleared__ for Consumption, from 1820 to 1831.

Brimstone.

Kates of Duty per Cwt.

Drawbacks onBrimstone

*

Years.

Importation.

Exporta .

tion.

Consump-

tion.

Unrefined.

Befined.

In Flour .

Gross

Revenue.

used in makingOil of Vitriol ,and on Brim­ stone exported.Repaymentson overEntries, &c.

Net Revenue.

Cwts.

Cwts.

Cwts.

£.

£.

£.

1820

93,003

14,121

112,057

0 15 0

10 0

1 3 9

i )

85,221

61,924

23,297

1821

1822

113,844

99,121

6,122

6,717

124,633

151,657

i >

) j

95,648

115,670

68,568

77,060

27,080

38,610

22,267

1823

172,495

2,293

153,841

* * .

117,637

95'370

1824

181,317

3,472

165,871

126',332

102^269

24,063

1825

218,722

4,860

268,433

|° o 6< Drawback

0 6 0on Brim

0 9* 9 \stone used >

75,306

118,830

.Excess of

1826

1827

251,981

218,359

6,817

16,385

233,093

207,462

tin making

Oil of Vitri

ol ceased. 1

5,903

5 275

13,821

32

l 43,524

do. 7,9185,243

1828

279,867

1,798

289,974

7 295

7

7,288

1829

302,084

941

314,182

7,886

4

7,882

1830

242,726

8,946

264,436

6,653

24

6,629

1831

289,446

4,992

296,095

7,480

28

7,452