CHAPTER XI.

SOME OF NED'S SCIENCE.

"How shall we cook our fish, Ned?" asked Charley, the next morning. He had already thrown wood upon the embers when Ned and Jack came out of the hut.

"We must roast them," said Ned, "now that we have no bacon to fry them with. We can broil sometimes and roast sometimes, for variety. Without b.u.t.ter broiled fish are rather dry. I'll be cook this morning, and show you how to roast small fish."

With that he went to the beach and walked along the water's edge till he found a bunch of clean, wet sea-weed. Returning to the fire, he carefully wrapped the mullets in this, and placed them in the hot ashes, covering them with live coals to a depth of several inches. Half an hour later he took them carefully out of their wrappings, and placed them on the log that did duty for a table.

The fish were beautifully done, and looked as tempting as possible, but, upon tasting them, a look of consternation came over Jack's countenance.

"I never thought of that," said Jack, "but we are out of salt! What shall we do? We can't live altogether on shrimps and oysters; and fish without salt is a difficult dish to eat."

"We must make some salt," said Ned.

"Out of the sea-water?" asked Charley.

"Yes. It is slow work, and without clarifying materials we'll get a rather black product, but it will be salt for all that."

"What will make it black?" asked Jack.

"Impurities. The sea-water is filled with various things--common salt, mostly, of course, but there are Glauber's salts, Epsom salts, magnesia, and many other things, including salts of silver and iron. In making salt out of sea-water, these impurities must be got rid of, or the salt will be of a dirty brownish color. We can't clarify it, but we can use it very well for all our purposes. We'll have to put up with a poor breakfast, but we'll do better by night. I'll start our salt-works immediately after breakfast, and then I'll leave Charley in charge of the business, because I have an idea of my own that I want to carry out.

We must devote ourselves to-day exclusively to the business of getting food, I suppose."

"Yes, that is the first thing to be done. We are at the starvation point and must get something to eat before we begin on the boat. What is the plan that you speak of?"

"I shan't tell you, because it may come to nothing, though I'm hopeful."

"All right, I hope it will turn out well. Meantime, I'll take the cast net and get some shrimps and possibly some fish, and then if I had any thing to bait with, I would set some rabbit traps or something of that sort. But I haven't, and so I can't. Charley can carry on the salt-works while you do whatever it is you mean to do."

The salt-works consisted of nothing more than the kettle. Filling this with clear sea-water, Ned set it to boil, saying:

"Now, Charley, as it boils down add more water, and toward night we can stop adding water and let the salt settle. It will begin to settle before that time, and when it does you can dip the wet salt up from the bottom and spread it out on a plank to dry."

"All right. I'll make a dipper out of a tin cup by fastening a stick to it for a handle. But what makes the salt settle?"

"Why, don't you see? You can only dissolve a certain amount of salt in a certain amount of water; if you put more in it sinks to the bottom, being heavier than water, and stays there. When a liquid has as much of any thing dissolved in it as it can hold, it is said to be saturated; we call it a saturated solution. Now when you boil sea-water it evaporates, and the quant.i.ty of water steadily decreases. After awhile so much of the water is evaporated that we have a saturated solution, and then if you evaporate half a pint more of it the salt that a half pint of water can hold in solution must settle to the bottom. It is a curious fact that water which is saturated with one substance, so that it can not hold any more of it, is still capable of dissolving other substances and holding them in solution. Sometimes, in making salt, men take advantage of that fact."

"How?" asked Jack, who had become interested in Ned's explanation.

"Why, by washing out the impurities of the salt with salt water. Having a quant.i.ty of impure salt they put it into a funnel-shaped vessel with a small hole in the bottom; then they take clear water and pure salt and make a saturated solution of that; this water cannot dissolve any more salt, but it is still capable of dissolving the other substances which const.i.tute impurities; so it is poured into the vessel that contains the impure salt, and as it pa.s.ses through it dissolves and carries off the impurities, but doesn't dissolve any of the salt."

"Why can't we purify our salt in that way?" asked Charley.

"Because we have no pure salt with which to make the solution."

"That's so, but I didn't think of it. I wish I knew as much as you do about such things."

"I don't know much," answered Ned. "I have always been curious to know facts of the sort, and my father has encouraged me to find them out. I ask questions and read what books I can on such subjects; but I learn most by looking and thinking for myself. Still I know very little about scientific matters; really I do. But we're wasting time; I must be off and so must you, Jack. Keep the salt kettle boiling, Charley, and don't forget to add water to it from time to time. When you pour cold water in you can skim the sc.u.m off, and in that way you'll get rid of a good deal of impurity."

With that the boys separated. Jack went down along the sh.o.r.e, with the cast-net in his hand; while Ned struck off into the woods with the coffee-pot, which, now that the boys had no coffee, was no longer in use at camp.

Jack returned about noon, bringing back a fine lot of shrimps, half a dozen fish, a few crabs, and some oysters, together with the news that he had discovered a large oyster bank which could be reached by wading at low tide.

Charley greeted him with a smiling face on which there was a look of triumph.

"Look here, Jack," he said, going to a plank upon which there were two or three little white heaps; "Ned is out in his science this time; I've got beautifully white salt as you see, and not the dark, impure stuff he said I would get; but that isn't all; instead of settling to the bottom of the kettle, it rises to the top to be skimmed off."

"Yes, I could have told you that," said Ned, who had arrived un.o.bserved.

"It's a way that it has. Taste your salt, Charley."

Charley did so, looked puzzled, and then turned to Ned.

"What is it, old fellow?" he asked.

"Why, beautifully white salt to be sure," answered Ned; "isn't that what you said it was?"

"Yes, I said that," answered Charley, "but now I know better. It is tasteless."

"Magnesia usually is," said Ned.

"Is that magnesia?"

"Yes, in the main. It is mixed a little with other things perhaps, but it is mostly magnesia. That is why I told you to skim it off. We don't want it in the salt."

"But I haven't any salt," said Charley, "I've filled the kettle up every fifteen minutes but no salt has settled yet."

"Your solution isn't saturated yet," said Ned. "This water contains only about two per cent of salt, or possibly in its impure state three per cent. To make one kettleful of salt we must boil away from thirty to fifty kettlefuls of water. The kettle holds two gallons, and so, in order to get a pint of salt we must boil away two or three kettlefuls of water. You have filled it up enough for to-day; now keep it boiling and we'll get a pint or two of salt, before night, and meantime we can pour a little of the boiled-down water on our fish for dinner, for I'm hungry."

"By the way, Ned," said Jack, "what luck have you had?"

"Good. I've brought back a coffee-pot half full, and have made arrangements for more to-morrow."

"Well, I like puzzles and riddles and things of that sort," said Jack, "but I hate to wait for 'our next month's number' for the answer. What is it you've got in the coffee-pot?"

"Bread," answered Ned, "or a subst.i.tute for it. I've been gathering the seeds of gra.s.ses and weeds."

"Seeds of gra.s.ses!" exclaimed Charley; "why, who ever heard of anybody eating gra.s.s seeds?"

"You've turned sceptic, Charley, since your faith in your beautiful white salt received such a shock," said Ned; "but still I think some gra.s.s seeds are occasionally eaten by men,--wheat, for example, and rice and corn."

"That's so," said Charley, abashed; "only I never thought of wheat and rice, etc., as gra.s.ses. But are wild gra.s.s seeds good to eat?"

"Yes, of course. All ordinary gra.s.s seeds are composed of substantially the same materials, and they are all nutritious. I have gathered about a quart, meaning to mash them up and make a sort of bread out of them; but there isn't time for that now, so I mean to boil them for dinner. The important thing is to have some kind of grain food to eat, and in that way we'll get it somewhat as if we had rice."