Building."

"Those papers proving his right to the oil land, which you recovered
from the sunken ship for him, must have made his fortune."

"Well, yes--that and other things," agreed Tom. "Say, we had some
exciting times on that undersea search, didn't we?"

"Did you call on Mr. Keith when you went to Newmarket with Mary?" Ned
wanted to know, for he and Tom had taken quite a liking to Miss
Nestor's uncle.

"No, I didn't get a chance. Besides, I wanted to keep away from the
Landmark Building."

"Why?"

"Oh, I might run into Field and Melling, and I don't want to see them
until I can accuse them, and prove it, of having taken Mr. Baxter's dye
formulae."

"Oh, yes, they're in the same building with Mr. Keith, aren't they? Why
do they call it the Landmark? Though I suppose the answer is obvious."

"Yes," assented Tom. "It's a big building--the tallest ever erected in
that city, and a fine structure. Though while they were about it I
don't see why they didn't make it fireproof."

"Didn't they?" asked Ned, in surprise. "Then the insurance rates must
be unusually high, for the companies are beginning to realize how fire
departments, even in big cities, are hampered in fighting blazes above
the tenth or twelfth stories."

"Yes, it was a mistake not to have the Landmark Building fireproof,"
admitted Tom. "And Mr. Keith says the owners are beginning to realize
that now. It is what is called the 'slow burning' construction."

"Insurance companies don't go much on that," declared Ned, who was in a
position to know. "Well, let us hope it never catches fire."

These were busy days for the young inventor. He laid aside all his
other activities in order to perfect the plans for manufacturing his
new chemical fire extinguisher on a large scale. For Tom realized that
while a small quantity of chemicals in a compound might act in a
certain way on one occasion, if the bulk should happen to be increased
the experimenter could not always count on invariably the same results.

There appeared to be at times a change engendered when a large quantity
of chemicals were mixed which was not manifest in a small and
experimental batch.

So Tom wanted to mix up a big tank of his new chemical compound and see
if it would work in large quantities as well as it did with the small
amount Ned had dropped on the blazing tree.

To this end Tom worked at night, as well as by day, and finally he
announced to Ned and Mr. Damon, who called on