The roots are washed, and then scraped, with a shell or knife, into a fine pulp. This pulp is placed in a loosely-woven bag of palm-fibre, which is suspended from a pole; a weight at the lower end of the bag brings a pressure upon the pulp, by which the juice is forced out. While the substance is still damp it is spread on metal plates, and dried over a fire; and great care must be taken to drive off every drop of the poisonous juice. During the drying it is stirred and broken into coarse grains, and this forms the _farina_, or meal of mandioca. The poisonous juice is placed in a vat, where it deposits a fine sediment after standing a few hours. This sediment is the tapioca which is extensively used in Europe and America for the manufacture of puddings and other articles of food. Arrow-root is another form of the same substance. The whistle recalled them, and they returned to the train. From tapioca the conversation turned to slavery; a very natural turn, as a good deal of the tapioca which comes from Brazil is grown by slave labor. "Slavery is in process of extinction here," said the Doctor, "as a system of gradual emancipation was adopted in 1871. There will be nothing left of the institution after the year 1892. Many slaves have been freed already, and it is thought that the northern provinces of Brazil will anticipate the enforcement of the law, and give freedom to everybody before that date. Most of the slaves are on the plantations in the southern part of the empire; some of the coffee-carriers in Rio are still held in bondage, and pay their masters a certain amount daily for their time. All they earn beyond that they retain for themselves." "How does the system of gradual emancipation affect the slaves at the present time?" one of the youths inquired. [Illustration: PUNISHMENT.] "It affects them unfavorably," was the reply, "as you can readily see. If a man has a lifelong interest in his slaves, he is apt to treat them well out of regard to his own pocket, by making them useful as long as he can. But if they are to be free in a given number of years, he is tempted to get as much work from them as possible during that time, and leave them broken down and quite worn out at the end. Sell a yoke of oxen to a man, and he will work them much less than if he had hired them for a year, and was not bound to return them in good condition, would he not? This is exactly the position of the slaveholder in Brazil; there are many humane masters who treat their slaves well, but, unhappily, they are in the minority. These people have been accustomed to regard the negroes as their property, and they use them as they would property of any other kind. Whether the slaves will be well or harshly used depends very much upon the temperaments of their owners. [Illustration: IN THE FIELDS.]