Chapter 29

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_ CHAPTER TWENTY NINE.

"And now, Tom," said Uncle Richard one day, "here we have a perfect speculum or concave reflector, but it does not reflect enough. What would you do now?"

"Silver it," said Tom promptly; "make it like a looking-glass."

"Exactly; but how would you do that?"

"Oh, it's easy enough, I believe," said Tom. "You get a sheet of tinfoil, lay it on a table, cover it with quicksilver, and then put the glass on it, and press it with weights till the tinfoil and quicksilver stick to the glass, and then you have a regular mirror."

"You seem to know all about it, Tom," said the Vicar, who had dropped in for a chat, and to hear how the telescope was going on.

"I read it somewhere," said Tom.

"And he can always recollect this sort of thing," said his uncle; "but never could remember anything to do with the law."

Tom looked at him reproachfully.

"Well," continued Uncle Richard, "your process would do for ordinary looking-glasses, Tom, but not for an optical reflector."

"Why, uncle?"

"Because the rays of light would have to pass through the thickness of the glass before they reached the reflecting surface,--the quicksilver,--and in so doing they would be refracted--broken-up and discoloured--so that the reflection would most likely be doubled when it came away; that is, you would see one reflection from the silver at the back, and another from the surface of the glass."

"Therefore," said the Vicar, "we must decline friend Tom's ingenious proposal, and take yours, Brandon, for as usual you have a plan ready."

"Well, yes," said Uncle Richard, smiling; "but it is due to the inventor. We must silver the glass, but on the surface, so as to get a reflection at once. Are you going to stay, Maxted?"

"If I may," was the reply.

"Very well; but for experiment, as it is all new to me, I think we will try first to silver one of these pieces of the broken speculum. Yes; that largest piece."

The conversation took place in the workshop, and the triangular piece of glass having been brought out, it was first thoroughly washed, and rinsed with rain-water, and then further cleaned by rubbing it well with a strong acid, so as to burn off any impurity, and after another rinsing in clear rain-water it was declared by Uncle Richard to be chemically clean.

"A good thing to be chemically as well as morally clean, Tom," said the Vicar, smiling; "but I'm not going to stand here without asking questions if you don't, Master Tom. First then, why must the glass be chemically clean?"

"So that the silver may adhere to it," said Uncle Richard, who was now carefully arranging the freshly-cleaned glass, so that it lay on two pieces of wood in a shallow tray half full of water.

"My turn to question," said Tom merrily.

"Yes, go on," said the Vicar.

"Why is the face of the glass put in water, uncle?"

"To keep it wet and thoroughly clean. Dust or floating spores might settle upon it, and then we should have specks. I want to get a surface perfectly clear; and now, Tom, I want the four bottles I prepared yesterday--fetch them down."

Tom ran up into the laboratory, and brought down four great stoppered bottles, each of which bore a label duly lettered.

These he placed on the broad, table-like bench, and on being requested hurried up-stairs again to fetch a large glass jar-shaped vessel, and a graduated measuring-glass.

"Now," said Uncle Richard, "this process is a chemical experiment, but upon reading it I felt that it was as good as a conjuring trick, and a very grand one too. In fact it is good enough for a magician, for it is a wonderful example of the way in which our chemists have mastered some of the secrets of Nature."

"Bravo, lecturer!" said the Vicar. "Come, Tom, my boy, give him some applause. Clap your hands and stamp your feet;" and the visitor led off by thumping his umbrella upon the floor.

"Oh, very well," said Uncle Richard, laughing; "it shall be a lecture on silver if you like--a very brief one, with a remarkable experiment to follow."

"More applause, Tom," said the Vicar; and it was given laughingly.

"I have here," continued Uncle Richard, "immersed in distilled water--"

"Rain-water, uncle."

"Well, boy, rain-water is distilled by Nature, and then condensed from the vapoury clouds to fall back upon the earth."

"Good," said the Vicar. "I am learning."

"Next," said Uncle Richard, "I have here a bottle marked A, containing so many grains of pure potash, dissolved in so many ounces of water--a strong alkaline solution in fact."

More applause.

"In this next bottle," continued Uncle Richard, "marked B, I have a strong solution of ammonia."

"Another alkali?" said the Vicar.

"Exactly," said Uncle Richard. "In this bottle, marked C, a solution of sugar-candy prepared with pure spirit. Can I have the pleasure of offering you a glass, Vicar?"

"Oh no, thanks," was the reply. "I will not spoil the experiment by satisfying my desire for good things."

"Will any other member of the audience?" said Uncle Richard merrily, looking round at Tom.

"I won't, uncle, thankye," said the lad. "You might have labelled the bottles wrongly."

"Wise boy," said the Vicar; "but, by the way, where's the lump of beaten-out silver to be affixed to the glass?"

"Here it is," said Uncle Richard, laying his hand upon the stopper of the fourth bottle, which held the same quantity of liquid as the others.

"But that's clear water," said Tom.

"Yes, clear distilled water, but not alone. It contains a great deal of silver."

"Whereabouts, lecturer?" said the Vicar.

"In solution," said Uncle Richard gravely. "Here we have one of the wonders of science laboriously worked out by experiment, and when discovered simplicity itself. Tom, suppose I take a piece of bright clear iron and leave it out exposed to all weathers, what happens?"

"Gets rusty," said Tom.

"Exactly; and what is rust?"

"Red," said Tom.

"So is your face, Tom, for giving so absurd an answer."

"Yes, uncle," said Tom frankly. "I don't quite know."

"Oxide of iron," said the Vicar.

"Oh yes," cried Tom eagerly; "I'd forgotten."

"Well," said Uncle Richard, "the oxide of iron is Nature's action upon the iron. Man produces iron by heat from the ore, but unless great care is used to protect it from the action of the atmosphere, it is always going back to a state of nature--oxidises, or goes back into a salt of iron. That by the way; I am not dealing with a salt of iron but with a salt of silver. There it is, so many grains of a salt of silver, which looked like sugar-candy when I wetted it in the water, and, as you see now, here it is a perfectly colourless fluid. There, I have nearly done talking."

"More applause, Tom," said the Vicar merrily.

"Come, that's hardly fair," retorted Uncle Richard. "What would you say to us if we applauded when you said one of your sermons was nearly at an end?"

"But we did not applaud the announcement that you had nearly done," said the Vicar, "but the fact that the experiment was nearly at hand."

"Yes; that's it, uncle. Go on, please," cried Tom.

"Very well then: my experimental magic trick is this," continued Uncle Richard. "I am about not to change a metal into a salt, but a salt-- that salt in solution in the water--back into a metal--the invisible into the visible--the colourless water into brilliant, flashing, metallic silver."

"The cannon-ball changed from one hat to the other is nothing to that, Tom Blount," said the Vicar; "but we are the audience; let's be sceptical. I'll say it isn't to be done."

"Oh yes," said Tom seriously. "If uncle says he'll do it, he will."

"Well done, boy," said the Vicar, clapping the lad on the back. "I wish my parishioners would all have as much faith in my words as you have in your uncle's. But silence in the audience. The lecturer will now proceed with the experiment."

"Yes," said Uncle Richard, taking the great glass jar. "Now watch the magical action of Nature, and see what is a great wonder. See, I pour eight ounces--fluid ounces, Tom, not weighed ounces--into the glass measure from this bottle. There: and pour them into this glass jar, which will hold eight times as much. From the next bottle I take an equal quantity and pour it into the jar; and from this bottle I take another equal quantity and pour it into the others. Shake them all up together, and I have so much liquid which looks like water, but, as you may have observed, one of them was the limpid silver solution."

"Yes, I saw that," said Tom.

"I didn't," said the Vicar; "but boys always do see the critical thing in the conjuring trick. But go on, Professor Brandon."

"I must come to a halt here," said Uncle Richard.

"No, no, don't say that, uncle," cried Tom. "You've raised us up to such a pitch of expectation."

"Only for a few moments," said Uncle Richard, "while I prepare my glass. Now then, when I lift out the piece, Tom, you take up the tray, and empty the water into the sink, and bring the empty tray back, place it where it was before, and then come and hold the glass here upon this blotting-paper to drain."

All this was done as requested, and then the lecturer was set free by Tom holding the three-cornered piece of glass, from which nearly all the water had run.

"Now observe," said Uncle Richard, "this is the critical point of the experiment. You see, I take this fourth bottle, and pour the same quantity of this clear liquid into my measure. There--done; and as long as I keep them separate no action takes place, but the moment I pour this clear liquid into that clear liquid, you will see that a change takes place. Look--I ought to say behold!"

The contents of the measure were poured into the glass jar.

"Gets cloudy and thick," cried Tom.

"And thicker and thicker," said the Vicar, as the contents of the jar were well shaken up, and then quickly poured into the tray.

"Now, Tom, the glass," said Uncle Richard sharply; and, taking a couple of little pieces of wood, he placed them in the tray at the sides, and then seizing the piece of broken glass speculum with the tips of the fingers of each hand, he quickly immersed the polished face in the fourfold solution, letting one side go in first, and then the rest of the face, till the glass rested about half an inch deep in the tray, its face being perfectly covered all over.

"Now watch," continued the lecturer; "the magic change has commenced, the metallic silver is forming," and as he spoke he kept on rocking the glass to and fro upon the two bits of wood.

"Why, it has turned all of a dirty black," said Tom, "and as thick as thick," as the rocking went on. "Why are you doing that, uncle?"

"So as to make a regular film come all over, and cause all the solution to be in motion, and give up its silver," was the reply.

"Is it a failure, Brandon?" said the Vicar quietly.

"I hope not," said Uncle Richard; "but of course I am a perfect novice at this sort of thing. It does look though as if I had made a mess instead of a grand experiment."

"Yes, the water has turned pretty inky and thick."

"Hurrah!" shouted Tom enthusiastically; and he caught up a duster and began to wave it in the air.

"What is it, Tom?"

"Hurrah!" yelled the lad. "Silver! Look, look!"

"I do not see any," said the Vicar, taking out his eye-glasses to put on, "only a greasy look on the top of the dirty water."

"No, sir, silver--silver," cried Tom excitedly. "I can see no end of tiny specks floating. Look, uncle. Don't you see?"

"Yes, Tom, you are right," said Uncle Richard, working away at rocking the glass to and fro.

"Oh yes, I can see it now, glittering on the surface," cried the Vicar, as excitedly as the boy. "Wonderful! quite large filmy patches floating. My dear Brandon, it really is very grand."

"Let me rock it now, uncle, to rest you," cried Tom.

"No; only a few minutes more, Tom, and then it may rest and finish."

"How long does it take?" said the Vicar.

"Oh, from ten to twenty minutes," said Uncle Richard; and at the end of a quarter of an hour, which had passed very quickly, so interested were they all, he ceased rocking the glass and left the face immersed in the murky solution, which had resembled very dirty blackish water, with faint traces of silvery film on the surface.

At the end of another five minutes the film was in larger patches, and at the end of another similar lapse of time Uncle Richard declared his experiment so far at an end, and lifted the piece of glass out dripping and dirty, leaving the water fairly clear, but with a thick sediment at the bottom, while the dripping face of the glass, instead of being brilliant polished glass, was seen to be coated over with a drabby-white or greyish film.

"Double up that piece of blotting-paper, and place it in the window, Tom," said Uncle Richard; and while this was being done, the darkened glass was critically examined by the Vicar.

"I'm afraid you won't see many stars in that, friend Brandon," he said.

"It does not look like it," replied Uncle Richard. "But let's get it dry in this current of air, and see what it is like then. Besides, there is something else to follow. That is only the rough surface of metallic silver. It has to be burnished before it is fit for use. That's right, Tom. There!"

The glass had been placed in the sunny window opening, and this being done, Uncle Richard washed his discoloured hands at the sink.

"Now," he said, "dinner must be nearly ready. Stop and have a bit with us, Maxted, and see what the experiment says afterwards. It will be dry enough to polish by then."

"Oh, thank you very much, but no, really I ought to--er--I did not mean to stay."

"Never mind, stop," cried Uncle Richard warmly.

"Yes, do stay, Mr Maxted," cried Tom.

"It's very good of you, but I think I ought to--"

"Stop," said Uncle Richard.

"Really, I should like to see the end of the experiment."

"And hear the end of the lecture directly after dinner," said Uncle Richard. "Tom, run in and tell Mrs Fidler to put another chair to the table. Mr Maxted will stay. Now let's have a walk down the garden till the dinner-bell rings." _

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