154 THE POTATO. 



It only differs from this substance in its color. Like indigo, it ac« 

 quires the metallic polish when rubbed with a hard body. It dis- 

 solves in alcohol, and in alkaline solutions ; it mixes readily with 

 grease, and it is with such a mixture that the Indians paint their 

 bodies. Chica has been employed in cotton-dyeing, and the color is 

 found to stand the sun perfectly. 



§ XL— COMPOSITION OF THE DIFFERENT PARTS OF 

 PLANTS 



The immediate principles, the history of which has now been 

 sketched, are met with in greater or lesser quantities in different 

 parts of plants ; some of them are accumulated in the roots, others 

 in the seeds, the barks, the leaves, &c. To complete the study of 

 the chemical constitution of vegetables we have still to examine 

 with reference to their composition certain parts or organs which 

 present sufficient interest either from their extensive employment or 

 their importance in an agricultural point of view. 



ROOTS AND TUBERS. 



The Potato, {Solarium tuberosum.) This plant is a native of 

 South America. Two English travellers, Messrs. Caldcleugh and 

 Baldwin, were so fortunate as to meet with it lately in the vild state in 

 Chili, and not far from Monte A^ideo. It is probable that the culti- 

 vation of the potato spread from the mountains of Chili to the chain 

 of the Andes, proceeding northward and obtaining a footing suc- 

 cessively in Peru, at Quito, and upon the plateau of New Granada. 

 This, as Humboldt observes, is precisely the course which the Incas 

 took in their conquests. The potato does not appear to have been 

 introduced into Mexico until after the European invasion of that 

 country ; and it is well ascertained that it was not known there un- 

 der the reign of Montezuma, although there are not wanting some 

 who maintain that the potato was found in Virginia by the first colo- 

 nists sent thither by Sir Walter Raleigh. It is said that it was then 

 brought into England by Drake ; but it seems well established that 

 long before Drake's time, namely, in 1545, a slave merchant, John 

 Hawkins by name, had introduced tubers of the potato from the 

 soasts of New Granada into Ireland. From Ireland the new plant 

 passed into Belgium in 1590. Its cultivation was at this time neg- 

 lected in Great Britain, until it was introduced by Raleigh at the 

 beginning of the seventeenth century. When the potato came from 

 Virginia to England for the second time it was already disseminated 

 over Spain and Italy. It has been ascertained that the potato has 

 been cultivated on the great scale in Lancashire since 1684 ; in 

 Saxony since 1717 ; in Scotland since 1728 ; in Prussia since 1738,* 



* Humboldt, Essai PoUtiqoo, t. ii. p. 46JI. 



