“O, more,” said Rollo; “we want more than that.”
“Yes,” said Jonas; “but we must take a little at a time.”
“Because,” replied Jonas, “if I put much into the mortar at once, I can’t make it fine. I must only have a little, and then the pestle and the bottom of the mortar come close together, and so it grinds up the smallest pieces.”
When Jonas had pounded up the charcoal which he had put in at first, he poured the black powder out into one of the tea-cups, and then put in more charcoal, which he powdered as before. He proceeded in this way until he had filled one of the tea-cups nearly half full. He then washed out the mortar, and put it down to the fire to dry. Then he took a glass jar, which Dorothy had brought him from the closet, and which was nearly full of a substance which looked like salt, and poured some of it into the mortar.
“Yes,” rejoined Jonas, “and tastes a little like salt.”
Rollo and James both wanted to taste a little of the saltpetre, and they did. In the mean time, Jonas had poured some of it into the mortar, and was grinding it up with his pestle; and, when Rollo asked him where saltpetre came from, and what it was for, Jonas said he did not know any thing at all about it, and went on pounding and grinding with his pestle.
Dorothy now brought out another jar, containing sulphur; and as soon as Jonas had finished pulverizing his saltpetre, and had put it all into its cup, he poured out some of the sulphur into the third cup. The jars and the mortar were now put away, and Jonas got two sheets of wrapping-paper, and put upon the table, for he said he thought it probable that they might want some, in trying the powder.
“I expect your father will want a pair of scales, too,” said Jonas.
“To weigh out the materials,” replied Jonas. “I don’t know what the proportions are; but I suppose that they must be mixed in right proportions.”
“What are the right proportions?” asked Rollo.
“I don’t know,” said Jonas, “but I suppose your father will know.”
“Well,” said Rollo, “I’ll go and call him.”
So Rollo went in, and told his father that they were all ready. He found his father at the library looking at a large book.
“Seventy-five parts of saltpetre,” said his father, reading out of his great book, and appearing not to pay any attention to what Rollo said,—“seventy-five parts of saltpetre, eleven and a half of sulphur, and thirteen and a half of charcoal. Seventy-five to eleven, that is, about seven to one. Say, six times as much saltpetre as of each of the other two. That will be near enough.”