"Are there other kinds besides metallic mercury?"
"Oh, yes; it may be in the form of a nitrate, a sulphate, a chloride or an iodide. The chloride is very poisonous, and is known as corrosive sublimate. It would be just the thing to rid the stable of the rodents that took the barley."
One morning the Professor called the boys together and informed them that it had been the custom to take a certain day each week for hunting or other recreation, and suggested that they continue the practice.
"I should like to go over to Observation Hill and see the flag you made," said Ralph. All agreed to this heartily, and the merry party set out, after being fully equipped, as was always the custom. Red Angel formed one of the party, of course, and in lieu of a gun, George had made a stick in imitation of one. He was immensely proud of this acquisition, and actually hugged it when it was presented to him. From that time forward it was his constant companion.
When the Hill was reached, Angel made for the pole, and with his gun in hand, scrambled to the top, giving out his peculiar chuckling noise, which indicated delight.
"Why the gun doesn't seem to make any difference in his climbing," exclaimed Tom.
They scanned the broad sea, and who shall say what their thoughts were as they silently stood there. For some reason when they started to go down the hill they were not so jolly as when going up. Their course was directed to the east, but just why no one knew. It seemed as though they were simply drifting, each with his own thoughts; but Harry soon banished their reveries.
"Let us follow the beach down to South River," he suddenly exclaimed, and all were glad that something had been said or suggested. It was so easy to turn them from gravity to cheerfulness, and probably Harry was trying some of the Professor's medicine on the boys.
At every step of the way, and in every action, the boys now realized that the work of the Professor had been imprinted on them. Tom and Ralph went along glancing superficially at the various objects, but it was entirely different with Harry and George. Every depression, and each succeeding elevation, or clump of trees, or any object beyond the ordinary, was closely scrutinized by them.
This course soon became noticeable to the boys, and called forth a comment from Tom. "Yes, we are always hunting for something. That was a trait which the dear old Professor taught us, and it would surprise you to know how many things we found out by that quality. We have always since found it a pleasure in doing so."