some risk of over-heating the sugar; therefore think of some better way. Instead of raising the temperature of the steam, consider whether you know of any means of making fluids boil, without increasing the heat."

Harry considered for some time, and at length said, "I have seen water made to boil when only moderately warm, by putting it under the receiver of an air pump.'

"How did that happen?" said his father.

"Because there was a vacuum," said Harry, "there was no pressure of the atmosphere. If we could place the sugar-pan under the receiver of an air pump, that perhaps might do; but the quantity of sugar to be boiled puzzles me, father; the sugar vessels are very large, I believe; I could only boil a very small quantity in an air-pump; so that after all it would not do, I suppose."

66

"Till

'Why will not it do?" said his father. you are sure that what you propose will not answer, never fly off to anything else. Do not give up your ideas too hastily. You should not fix your imagination upon the particular receiver of the air-pump you have seen. To be sure you could not conjure a sugar-boiler into that small receiver."

"No, to be sure," said Harry, laughing: then becoming quite grave again, he went on thinking. "How shall I manage it? It is impossible to blow a glass large enough for the receiver."

"Why do you stick to the notion of a glass receiver, Harry?" said his father. "Do you think it essential to the having a vacuum, that it should be produced in glass ?"

"Certainly not," said Harry, "it is not necessary by any means. I only thought of the glass one, because that was the only receiver I had seen; but I perceive that any other substance that is air-tight will do as well as glass. How foolish I am! I remember now the pump, and the steamengine, where the vacuum is large enough; or a vessel might be made as large as could be required for the purpose."

"Now you have it, Harry. The sugar is boiled in a vacuum, and that vacuum is produced by means of an air-pump. The exact details I do not know, having never seen it done myself, but I hope we shall see it to-day, and so now let us set out."

79

SUGAR-REFINING.

THE sugar-house which Harry and Lucy went to see was a large building of eight stories high. The first circumstance which struck them on entering it was, that in several spacious rooms through which they passed, and in which the work seemed to be going on, there were not many workmen. Lucy supposed that it was the hour of dinner, as had happened in some other manufactories which they had seen: but she was told that this was not the case; and that all the men who were ever employed in this sugar-house were now there. Few only were necessary, because so much was done by machinery. In truth, the men seemed of little importance. It appeared as if they were employed only as under-servants to the machines, and to do trifling things, which the mechanic and the chemist had not thought it worth their while to invent the means of effecting in any other way.

The large rooms and passages, through which they passed, were all warm, as Lucy observed, and yet she could not perceive a fire anywhere. She asked how they were warmed, and was told

steam that passed

that she would soon see, as they were going to the place from whence the warmth came. Their guide, the gentleman who was so kind as to show them these works, took them to a building, separate from the rest, in which there was a steamengine. The fire under its boilers was the only fire used in these works. All the rooms were sufficiently heated by the through pipes to the different sugar vessels. Harry was here perfectly satisfied, and he looked delighted and proud when he heard how much was performed by one steam-engine. It sent over this vast building equable warmth, and supplied all the water that was wanted in every part of the works. It put in motion a mill for crushing the sugar, and other substances used in refining it; and it kept in unremitting action the pistons of a huge air-pump.

They followed their guide into a sort of outhouse, in which the earth of alum was prepared, by adding quicklime to a solution of it.

They then entered that part of the building where the preparatory operations of cleansing the sugar were performed. They saw in the first place a few workmen with naked arms, and in light clothing, suited to their hot work, stirring with huge shovels in a great pan the raw brown sugar, such as it is when brought from the West Indies they were stirring it up with a small

:

quantity of water, not sufficient to dissolve it. It looked like treacle. This was afterwards poured into earthen moulds, of which there were great numbers in the shape of sugar-loaves, such as those of which they had read a description, with a hole at the point, which was turned downwards; and in these moulds it was to be left twenty-four hours to filter. In the course of that time the molasses would pass through into jars beneath the sugar-loaf moulds, and the sugar left behind would be in solid lumps, of a light brown colour. Some of the sugar thus purified was put into Lucy's hand; she felt that it was soft enough to be readily crushed. It was now to be dissolved in water, which was heated by having steam passed through it. The earth of alum, which they called finings, was then added to this solution, and thoroughly stirred about by passing currents of steam through it.

This was performed in a great square cistern, which had a double bottom and sides, with a space left between, sufficient to introduce the steam. The inner bottom and sides were perforated with minute holes; and through these holes the steam passed up into the liquid sugar. They heard a rapid succession of explosions, occasioned by the sudden condensation of the steam; and, when the solution became hot, they saw immense volumes of steam rising through it. After this, the syrup