Soap Bubbles, Chapter 15

          The next day every child came to school with a knobby bundle.
          When these were opened on Miss Dean’s table, what a collection there was!
          There were scouring soaps in cakes and in pastes, there were liquids and powders. Some were for scrubbing the hands, some for silver, some for brass or copper or other metals, and many were for general uses. And what do you suppose Mary had brought?
          She had brought some tooth powder and tooth paste!
          “Bright girl, Mary,” said Peter.
          “Well, you see,” said Mary, “mother often tells me to scrub my teeth clean, so I thought tooth powder or paste belonged with these other scrubbers.”
          Just then Miss Dean placed a microscope on the table.
          John said, “Oh, I’m glad we’re going to look through a microscope again. Father lets me look through the one he has in his office. Tiny things that I can hardly see with my eyes look big through the microscope.”
          “Would you all like to look through this microscope by and by?” asked Miss Dean.
          “Oh, yes! May we? What shall we look at?”
          “Wait until our industrial science period, when we begin to study our scourers, and I think we shall find a use for it,” Miss Dean answered with a smile.

          Waiting? It wasn’t easy, with a microscope waiting too and looking so interesting. But by and by arithmetic and spelling were done, and the class was invited to come to the table.
          “May we see this scourer? And this? And this?” were the questions that came thick and fast.
          “Yes, and yes, and yes. Each shall have a turn,” said Miss Dean. “But first let us put all the scourers together which belong together, the tooth powder and paste in this place, the silver polishes in another place, and so on. Then we can study each group more easily.”
          The children began at once to read the labels, to aid in the sorting.
          Very soon Peter said, “Why, I didn’t know so many things could be scoured. This can of powder has a list of nineteen things which it scours.”
          “Then it is certainly one of those for general use,” said Miss Dean. “We have a number of those. Often they are in cans with tops in which holes may be punched, to shake out the powder.”
          “This can of scouring powder says it doesn’t scratch,” said Jimmy.
          “The silver polishes say that, too,” said George. “I’ve just looked to see.”
          “We certainly want that to be true of the polishes we use for our silver, as well as for nickel and other fine metals,” said Miss Dean.
          “What about scratching teeth?” chimed in Jane. “This tooth paste says it contains no gritty matter.”
          “What may happen, if the enamel of the teeth becomes scratched?” asked Miss Dean.
          “Decay! Holes! Our dentist tells.”
          “Well,” said Miss Dean, “we have found out that each of these cleansers contains something which scours or polishes, and that it is often something which does not scratch. I think the microscope will help us to see just what that something is.
          “We will get ready to look at our scourers under the microscope by first stirring a little of each kind in one of these tumblers of water. Let the mixtures stand for a few minutes.”
          “Look at the suds we get,” said several children.
          “That tells us --?” asked Miss Dean.
          “It tells me that the scourer contains soap,” said Jimmy. “Soap makes soapsuds.”
          “Right. Do most of these scourers contain soap?”
          “Yes, Miss Dean.”
          “Then let’s remember that. Now look at the bottom of your tumblers.”
          “There is something which looks like powder on the bottom of mine,” said George.
          “On mine, too,” said several children.
          “But ours looks more like sand than powder,” said George and John.
          “What you are examining at the bottom of your glass is the scouring part of the cleansers, or what we call the abrasive,” said Miss Dean. “It does not dissolve in water, but settles down. Sometimes, as you see, it is fine, like powder, and sometimes coarse. The microscope will show us just how each kind of abrasive looks when magnified.
          “Now carefully pour off most of the liquid in your tumblers, leaving the abrasive behind. When you have done that, I will put a little of each on these thin plates of glass, which we call glass slides for the microscope, then cover with these tiny, thin squares of glass, and then we shall be ready for each child in turn to see how our abrasives look when they are greatly magnified.”
          “May I see my tooth paste?” asked Mary. “I have poured off the water, and what is left looks and feels like flour.”
          “That ‘flour’ may have lived in the ocean,” said Miss Dean, with a smile at Mary’s look of surprise. “Here it is under the microscope.”
          “Why, it’s hundreds of little dots like tiny pin heads,” the children exclaimed as each took a look at Mary’s “flour.”
          “Yet each of those dots has been made by the microscope to look a great many times as long and as broad as it really is,” said Miss Dean. “Do you begin to understand how much a microscope like this magnifies, and that we could not see the separate dots with our eyes alone?
          “Let’s try to draw a picture of this toothpaste abrasive on the blackboard,” said Miss Dean, “if you think you make the dots look small enough. Then we can draw what other pictures as we see the, and compare.”
          “I don’t see how anything so small can have any size or shape at all!” exclaimed Jimmy.
          “I shall not be afraid that my teeth will be scratched by that toothpaste,” said Mary. “But, Miss Dean, what did you mean about these tiny things living in the ocean? Please tell us.”
          “I shall, later,” said Miss Dean, “but while we have the microscope ready we will look at some more of our scourers. Let’s see what the silver polishes look like.”
          Again the children looked, and saw tiny dots which seemed very much like those in the toothpaste, except that some were a little larger and more pointed in shape.
          “Does this come from the ocean, too?” asked Mary.
          “Yes, Mary,” Miss Dean answered. “Many of our silver polishes and some tooth powders and pastes contain the same kind of abrasive, but it may be a tiny bit coarser for silver and yet not scratch.”
          Then John went to the board and carefully drew a picture.
          “Here is a silver polish which has a deep pink color,” said Grace. “What makes it pink?”
          “That may be some color which has been added to it, or it may be the color of the abrasive itself,” said Miss Dean. “We will look at that next under the microscope.”
          The microscope showed tiny little specks as small as those in the toothpaste, and they were red.
          “What are they?” asked the children.
          “That abrasive is a form of iron called a red oxide of iron,” said Miss Dean. “It is used in several of the best silver polishes, and as you see it is so fine that it cannot scratch. Jewelers use it a great deal for polishing jewelry, so it is often called ‘jeweler’s rouge.’ ‘Rouge’ is a French word meaning red.
          “Now let us see some of the scourers for polishing other metals, such as brass and nickel, and some which are for general use.”
          The next few minutes were busy ones, and the pictures grew on the blackboard. There were some abrasives which showed rounded specks which were quite tiny, mixed with some that were coarser. And there were some that looked like tiny pieces of broken window glass, they were so thin and flat. And some that had small bits of different shapes and sizes. And some that looked and felt like sand.
          “Just think of using that powder on silver!” said Peggy.
          “But of course you wouldn’t,” said Miss Dean. “These coarser powders were never intended for fine metal surfaces such as silver and nickel, nor for porcelain or anything so smooth that it shows scratches easily. They are meant for other uses which we will find out about later. You must remember, too, that what you see under the highest power of this microscope is over three hundred times longer and broader than it really is.”
          George’s eyes turned toward a fly which had lighted on the table.
          “I’m thinking what that means,” said he. “Just suppose that fly suddenly became four hundred times as long and as broad as it is!”
          “It would look about twice as big as you,” laughed Miss Dean.
          “Then I’d get right out of this room as fast as I could,” said Grace.
          “Well,” said Miss Dean, “we have seen what abrasives look like when they are magnified, but of course most of us cannot have microscopes at home to tell which scourers may scratch. So next time we will try to find a way to judge our scourers at home.”
          ”Miss Dean,” said Mary, “you said you were going to tell me about my powder growing in the ocean.”
          “I haven’t forgotten, Mary, but we will leave the answer for another talk, and I know some of you have other questions which you would like to ask. Will you bring in your questions tomorrow?
          “And another important thing: If you have a piece of silverware or other metal, such as copper or nickel, or anything which needs polishing, bring it tomorrow, and we will choose the right kind of polish and learn how to use it.”