evaporation.

S6

Messrs. Kenrick of West Bromwich having produced in their factory and sent >the market some excellent specimens of enamelled saucepans of cast iron, were sueMessrs. Clarke for an invasion of their patent rights; hut after a long litigationchancery., the patentees were nonsuited in the court of exchequer. The previous Pcess of cleansing with dilute sulphuric acid appeared by the evidence on the triuhave been given up by the patentees, and it was also shown by their own P rll j. ^,5scientific witness that a good enamelled iron saucepan could be made by Hick* 1 t ^specification. In fact, the formulae by which a good enamel may be compounded ^almost innumerable; so that a patent for such a purpose seems to be untenable, 0least most easily evaded. I have exposed the finely-enamelled saucepans of veKenrick to very severe trials, having fused even chloride of calcium in them, an “found them to stand the fire very perfectly without chipping or cracking. I co f S j n tosuch a manufacture to be one of the greatest improvements recently introduced ^domestic economy; such vessels being remarkably clean, salubrious, and adapt ^the most delicate culinary operations of,boiling, stewing, making of jellies, P res , e or di'&c. They are also admirably fitted for preparing pharmaceutical decoctions, andnary extracts. „ la6 s

The enamel of the said saucepans is quite free from lead, in consequence ot tn & ^which enters into its composition being quite free from that metal. In severalsaucepan* which were at first sent into the market by Messrs. Clarke, their ^ 0 fwas found on analysis by several chemists to contain a notable proportion of oX ^ aS s olead. In consequence of the quantity of borax and soda in the glaze, this 0X1 - n the* 11readily acted upon by acids, that sugar of lead was formed by digesting vineg ar 1 j e git-with a gentle heat. The presence of this noxious metal formed, in my opim° n > ^ t fieimate ground for contesting the patent, being in direct violation of the terms j oU sspecification. Messrs. Kenwick’s wares have been always free from this del ^metal. Messrs. Clarke, I understand, have for some time been carefulto J^ture a ' 9 °their enamel-composition all glass which contains lead; and they now manutac p 0 j n twholesome enamelled ware. Thus the public have profited in a most import 11by the aforesaid litigation. ,, an^

Enamelled iron saucepans had been many years ago imported fromsold m London . I had occasion to analyze their enamel, and found to en t h aSthat it contains abundance of litharge or oxide of lead. The Prussian S oveI V- ^areS 0issued an edict prohibiting the use of lead in the enamelling of saucepans, wn gen t toextensively manufactured in Peiz, Gleiwitz , &c. Probably the German w ar a JoseEngland was fabricated for exportation, with an enamel made to flux easily -^jch Iof litharge. The composition of the said enamel is nearly the same with th a ^ j, e enfound upon some of the earlier saucepans of Messrs. Clarke. Had their P a ' atentefsustained, the important legal question would have arisen, whether it gave th ^jtuaU)the power of preventing dealers from continuing to sell what they had beendoing for a great many years. laveth e ^° ”

A suitable oven or muffle for lining or coating metals with enamel may 'lowing dimensions :— 1 f t sq uare **

The outside, 8 feet square, with 14-inch walls; the interior muffle, 4 lee^ ^ jjiehesbottom, rising 6 inches at the sides, and then arched over ; the crown may An° tbe jhigh from the floor : the muffle should be built of fire-brick, 2| inches thie an^

arch is turned over the first one, which second arch is 7 inches wider at 11 ^ jj s centr4 inches higher at the top. A 9-inch wall under the bottom of the Jong- x j

divides the fireplaces into two, of Hi inches width each, and 3 feet 3 inc f roB t, anflame of the fire plays between the two arches and up through a 3-inch n ( i, e ge oP eissues from the top of the arch through three holes, about 4 inches squa >

first

into a flue, 10-)-» inches, which runs into the chimney. . rp

mixed toeefher S /T enaIS . el body (ground P°tter>s clay ’ and W 3

feet 4 l io • h t n P ^- lnt ° a reYer beratory furnace, 6 feet 6.inches loB*, ^

hearth T1 d i -"V* 68 hlgh ’ The flame from 18-inch fi™P lace Pf se ! h fck, <* d

i-nftednr fill Tr en r ls aie spread over the floor °f the oven ’ about 6 in fl ke yea**’when anoihi f ° Ur ° r five hours > until begin to heave and work 1&J 0 „

the wlmle n C °Tc n - g f PIU on the t0 E- a]so 6 inches thick, and fired again, in

the muffles ^The^i* 1 be . fired t0 ° ranch, it becomes hard and too refractory co mr ose ‘!of -lhniit one n ir v g ' aze Is worked in an oven similar to the above. It may roC ure*lfrom the unite! and 0ne half ° f Cornish stone in a yellowish powde ^ is

ornoJi p< A tte ”, es ’ Thls >s fritted for 10 hours, and then fused into a glassground up for the glaze. ’ d c0 n-

EVAPORATION. For the following scheme of generating, purifying j an tiad’’*rk, merchant, London , obtained a patent , fresh- - — "omically into S 00 ,„ ic8 tes

densing steam, Mr. Charles Clark,

1843. His apparatus for converting sea-water, &c., econom comm

water, is represented in figs. 46, 47, 48. A is the supply-cistern,

i »nic a