when submitted to the pressure of steel rolls in the next operation.

For this purpose the sheets are piled up on square cast or wrought-iron stands, and over them, when the pile is complete, a cast or wrought-iron cover is placed, and in this condition they are placed to soak for ten hours in large reverberatory furnaces. This is a delicate operation, and requires great judgment; too much or too little heat is equally injurious. When the operation is well done they come out as soft as lead.

Cold Rolling.

This process is employed in order to obtain a smooth and even surface for the iron sheets before they are sent on to receive the coating of tin, and the finish of the tin-plates depends very much upon the way in which they have been cold-rolled.

If the cold-rolls are in good order, and they leave with a handsome set and finish, the appearance of the tin-plate will be all that is desired. If, on the other hand, they are buckled and streaky, all the tin-house care in the world can never improve them.

Each sheet is passed by boys through three pairs of revolving steel rolls successively, which suffices to polish the surface; but at the same time renders them harsh again.

Second Annealing.

To remove the harshness created by cold rolling, and in order to render the sheets soft and tough when they leave the works as tin-plates (qualities very much desired by those who convert them); the plates, after cold rolling, are again piled up in iron boxes, similar to those which have been described for the first annealing, and are again placed in the annealing furnace for ten hours, which is sufficient to remove the harshness arising from cold rolling, and renders them soft enough for future use as tin plates.

White Pickling.

The surface of the sheets having been hardened by the process of cold rolling and by the action of the fire in annealing, in order to prepare them for coating it is found necessary to give them a second bath of vitriol, but not nearly so strong as in the black pickling process.

The result of this second pickling is to remove the outer skin of the sheet, and to leave the pores open to absorb the molten tin.

After pickling, the sheets are washed and scoured by girls and women, and placed in tanks of fresh cold water to protect them from rust and dirt; in this condition they are ready for the tin-house.

The Tin.

The tin with which these plates are to be coated, comes to Wales either from London or Cornwall, for there are no tin smelting works in Wales.

From Cornwall it is always sent in the shape of refined blocks, each block bearing the stamp of the duchy (the wellknown lamb and flag), and also the name of the smelter from whom it is purchased; these blocks, which are very much of the same size, vary very little in weight, which may be stated at 400 lbs.

To London, as the market of the world, is sent all, or very nearly all, the foreign tin which is produced, and the consumer may purchase Straits tin from Penang and Singapore, Banca or Billiton tin from Java via Rotterdam, Australian or Tasmanian, at his own discretion.

Formerly, foreign tin was very indifferently smelted, and it was necessary for consumers to refine it, involving loss of weight in addition to loss of time (and consequent expense), now it arrives well refined, free from scruff, of good colour, and for quality very much the same wherever it comes from. Foreign tin is always bought and sold in ingots; it is of better colour and runs thinner than English tin, and on this

account it is generally employed to give the finishing coat to tin plates, English being used for the foundation or first coating, which is given by soaking in the tinman's pot; to give the last coat it is sufficient for the washman simply to dip the sheet in tin.

The quantity of tin used at a tin-plate works is about 5 tons weekly, for a quantity of 2000 boxes of terne and tin plates.

The Palm Oil.

The palm oil employed for this business comes from the West Coast of Africa via Bristol to Wales, in large casks containing about half a ton.

It varies in quality, as most things do; a preference is given to what is called selected Lagos oil, which goes farther, probably containing less dirt and water than the commoner sorts.

The bulk of the palm oil produced by our coloured brethren on the Gold Coast is either used for this purpose or for the manufacture of soap.

Tallow is equally well adapted for all practical purposes, but the unpleasant smell which results from melted tallow makes it impossible for workmen to employ it with any comfort.

The Tin House.

The affinity of tin for iron, and vice versâ, is a subject which has been frequently discussed in dissertations upon metallurgy; but we do not propose to follow up this subject, any more than to point out that the coating of three million boxes of tin-plates per annum is sufficient to demonstrate that the affinity is very great, and that the iron is well protected by the thousands of tons of tin which cover it.

The apparatus and appliances which are necessary for coating iron are termed a "set of pots," which are placed in brickwork with fire-places below the ground, the flues from which work into a large open-mouthed chimney or stack about 45 feet high (one for each set), which serves to carry