PART II.

"Now," said Jim, "to-day is Thursday, and if you can mix the sensitive bath, I will go down town and buy the other things that we need. Then to-morrow we can prepare everything, and Saturday--oh, just think!--we can take a picture."

After Jim started off, Fred went to the dark chamber, which was a large closet in their work-room, and at once set about preparing the mystic solution to sensitize the plate.

He first took some rain-water, and let it drip through a filter paper placed in a glass funnel, to remove all the impurities that might be suspended in it. Then he added the crystals of nitrate of silver; then a few grains of iodide of potassium were added, when, to his surprise, a yellow powder began to form. However, he put the mixture aside to saturate, as the Professor had directed him, having first stirred it with a small glass rod, and went to study his lessons for the next day.

He had not been studying long before Jim entered, and with a very grand air placed several small parcels on the table. He was about to explain their contents, when he suddenly broke out in a wild fit of laughter. "Why, Fred, what have you done to yourself?" said he.

Fred looked up from his book, and found, to his great disgust, a number of heavy black spots on his hands and coat. "Well, I don't see what that is," he said.

"I do," said Jim: "you have been and spattered yourself with silver, and the sunlight has turned it black. You are in a nice fix, for nothing will take it off."

"The coat was only a work jacket," said Fred, "and I don't care a bit about my hands. But let us see what you have bought."

"In the first place," said Jim, opening his packages, "here are some tin plates--great big fellows, too, and all for fifty cents. And here is some collodion. These green crystals are sulphate of iron, and the man says we must keep them in a very tight bottle, because if the air gets at them they will spoil. He told me they were made of old nails and sulphuric acid. Do you believe it? These green crystals we must dissolve in water before using. This stuff in the bottle is acetic acid. Doesn't it smell queer? And here is some hyposulphite of soda; and that's all. Now let's get to work."

The two hours were now over, and Fred returned to his silver bath, and let it run through a filter, when, by rule, the bath was ready. It was placed in a flask, and tightly corked.

"Now, Jim," said Fred. "I guess we would better leave everything until Saturday, because to-morrow we have an examination in algebra, and ought to cram for that to-night; and to-morrow afternoon is the ball match, and in the evening we shall be tired."

At last Saturday morning came, bright and sunny, and the two boys began in earnest the task of taking a picture.

Fred had procured a tall narrow glass vessel to hold the silver bath, and a glass dipper with which to suspend the plate, and having mixed the developing and fixing solutions, the boys were at last ready.

"Now you pour on the collodion," said Jim, "and put the plate in the bath, while I get the camera in position and adjust the focus."

"What are you going to take?" asked Fred.

"I guess I'll try old Spriggins's back yard," answered the other. "He's got a big grape-vine arbor there that will take immense."

Fred, left to himself, poured the collodion over the plate, and gently tilted it from side to side. The liquid did not flow evenly, but lay in rings and streaks all over the surface.

"Why didn't we try the Professor's gum-arabic, and save collodion!" he exclaimed. But not discouraged by failure, he tried again, and by sheer luck succeeded in making a smooth surface. In about five seconds he put the plate in the bath, and awaited the result. When he removed it, instead of being finely coated with silver, the plate appeared cracked, greasy, and spotted.

"Oh, misery!" he cried, "the bath is all full of yellow stuff. What shall I do?"

Hearing this, Jim returned to the laboratory, and with his usual calmness simply said, "Filter."

Fred did so, and in a few moments a clear bath was again obtained.

"How did that happen, I wonder?" said Fred.

"I don't believe you allowed the collodion time enough to set," was the answer. "Let me try this time."

After a good deal of trouble with the collodion, Jim finally prepared a smooth plate, which he allowed to wait thirty seconds, and then carefully lowered it into the silver bath. After a few seconds he raised it, and found it covered with streaks.

"Put it back," said Fred; and in it went. In about thirty-five seconds more, it was of that fine opal tint mentioned by the Professor. It was then placed in the slide and carried to the camera. Jim pulled out his watch, and with a forced smile to hide his nervousness said, "Go," and Fred drew up the sliding door. When the plate had been exposed long enough, as he thought, Jim cried, "Time," the door was closed, the slide taken from the camera, and the boys returned with it to the dark chamber.

The plate was then taken from the slide, and Fred, seizing a bottle, poured its contents over the opaline surface.

"As if by magic--" Jim began.

"Nothing appears," continued Fred, as he saw in astonishment every trace of silver disappear from the plate, and the bare tin surface left exposed. "I can't see through that," he added, in dismay.

"I can," answered Jim: "you were in such a hurry that you poured on the fixing solution instead of the developer, and of course that has dissolved everything."

Jim then prepared another plate with great care, placed it in the camera, exposed it for such time as he thought fit, and returned with it to the dark chamber. Removing it from the slide, he carefully poured on the developer. By degrees the cloud on the surface dissolved, and a picture slowly appeared, very imperfect, but still a picture.

"Isn't that splendid?" said Fred, enthusiastically; "it's just as natural as life."

Jim, cool and quiet as usual, washed the plate well with water, and cautiously poured on the fixing solution, when the yellow coating of the picture vanished, and old Spriggins's grape arbor came out in clear, sharp lines.

"Now, Fred," said he, "you calm down a little, and varnish this."

"All right," answered Fred; and having lighted the spirit-lamp, he poured on the varnish, and held the plate over the flame; but, alas! there was a fizz, a vile smell, a great deal of smoke, and the pretty picture was a mass of paste.

"I won't have anything more to do with this part of the work," said Fred, impatiently, throwing the spoiled plate on the floor. "I can play doctor's shop, and mix up solutions as well as anybody, but this endless dipping, washing, and drying takes more patience than I possess. I shall leave that to you, Jim."

"One more trial, and a perfect picture," answered Jim, quietly.

The next attempt proceeded smoothly up to the varnishing-point, when Jim said he would do it without the aid of heat. The picture was accordingly varnished and stood away to dry, when after a few minutes it was found to be covered with a white film which entirely obscured it. Fred declared he would never try again, but Jim, more persevering, decided to heat the plate a little, and see what happened. He passed it gently over the spirit-lamp flame, when, to his great relief, the cloud vanished, and the picture re-appeared, increased in brightness, and covered with a coating thick enough to protect it from scratches.

These boys had many other mishaps and disappointments before they became skillful enough to be sure of obtaining a good picture. They learned, too, that rules in books sound very easy, but that much practice and experience are required to carry them out successfully. But having by care and perseverance once conquered all obstacles, they had no end of fun copying pictures for friends and school-mates.

Having become very fair tin-typers, they are now ambitious to take negatives on glass, and print from them. If they succeed in doing this well, some day they may tell you all about it, if you are interested enough to listen.

[Begun in No. 58 of HARPER'S YOUNG PEOPLE, December 7.]

TOBY TYLER;

OR, TEN WEEKS WITH A CIRCUS.

BY JAMES OTIS.