LAMPS.
741
O e ^*- er j washed in pure water, mixed with a little gum water, and made into cakes,it 1 ® raz .^ wood may he boiled along with a'little vinegar, the decoction filtered, alumof R • at ^ e< ^> and then P 0 tash-ley poured in to precipitate the lake. For 1 pound
in y°od, 30 to 40 pounds of water, and from If to 2 pounds of alum, may he taken,tin^r U °' n “ a ^ ee P rcd kike ; or the same proportions with half a pound of solution of" the potash be added in excess, the tint will become violet. Cream of tartaroasions a brownish cast.
as I a ^ Cr ^ ce '—A f> ne lake may be obtained from madder, by washing it in cold water. .™? as it gives out color; then sprinkling some solution of tin over it, and setting i,:
iue for some days. A gentle heat may also be applied. The red liquor must be then' ? ara ted by the filter, and decomposed by the addition of carbonate of soda, when a fineof l^ ec *Pl ta te will be obtained. Or, the reddish brown coloring matter of a decoctionq ma< lder may be first separated by acetate of lead, and then the rose-red color with alum.Pot D J a ^ er l' ef l up in a bag is boiled in water; to the decoction, alum is added, and thenVpii ‘ ^’he precipitate should be washed with boiling water, till it ceases to tinge itand it is then to be dried,he following process merits a preference :
min a use ^ Pounds of ground madder in 4 quarts of water, and after a maceration of 10up UtCS ’ s * ra * n and squeeze the grounds in a press. Repeat this maceration, &c. twicej*. 011 the same portion of madder. It will now have a fine rose color. It must then bea w 6a ^tth 5 or 6 pounds of water and half a pound of bruised alum, and heated u]jonthe t, r ba,}l ter 3 or 4 hours, with the addition of water, as it evaporates, after whichthr Wa °t e must be thrown upon a filter cloth. The liquor which passes is to be filteredthree^* 1 t )a P er > a nd then precipitated by carbonate of potash. If the potash be added inl, e successive doses, three different lakes will be obtained, of successively diminishingn> ty ’ The precipitates must be washed till the water comes off colorless,mari Ue ^ es are hardly ever prepared, as indigo, Prussian blue , cobalt blue, and ultra-gUe, answer every purpose of blue pigments.v ello Cen ^ ce ® are made by a mixture of yellow lakes with blue pigments ; but chromer ^'J^uiixed with blues produce almost all the requisite shades of green.t, ar( l "TNABLF. is said of a metal which may be extended by passing between steel or(chilled) cast-iron rollers.
For a ^ escia P l >°n of metal rolling presses, see Iron and Mint ; andj,» a ta hle of the relative laminability of metals, see Ductility.g tee ‘ALBUM, or the dead nettle, is said by Leuchs to afford in its leaves aSreen! S r y - ellow d 5 e - The L. purpureum dyes a reddish-gray with salt of tin, and a^nt with iron liquor.
tiou - differ so much in principle, form, and constmctiOn, as to render their descrip-l aiT mj s . Possible, as a general subject of manufacture. In fact, the operations of theturner tbose the blacksmith, cabinet-maker, cooper, coppersmith, tinman,
du ee ’ &c -> belong to a treatise upon handicraft trades. I shall here, however, intro-,abal - view of the relative light and economy of the lamps most generally
J Kia <l Of Lamps.
Intensity of light during
Mean of
7 hojirs.
Consump-tion perhour ingranules.
Light from100 partsof oil.
hour
2
hours
3
hours
4
hours
5
hours
6
hours
| .blechanical lamp of: , Carcel
• Fountain lamp, )
j aad a chimney >
3 r) Wltb flat w ‘ c k )
4 "°nne argand
o' j-j nurn bra lamp .
• with fountain
6 above
' D °- with another- beak -' Girard’s hydrostatics tamp-
Thilorier’s or Par- )km ’s hydrosta- (Uc lamp - ^
too
103
102
100
100
101
106
98
90
95
90
97
96
103
98
72
83
70
95
84
100
97
61
'81
52
92
81
94
96
42
78
41
89
76
92
96
34
66
32
86
70
90
100
125
31
56
85
41
63'66
107-66
42
11
26-714
37-145
43
18
34-714
51-143
238
113
116
150
197
227
182
215