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Page:Popular Science Monthly Volume 15.djvu/664

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THE POPULAR SCIENCE MONTHLY.

The best practice in these plantations is to train the plants on espaliers reaching from one prop to another. Generally the props are themselves plant-cuttings, which bear leaves and so shelter the young plants from the excessive heat of the sun. In case the props are of dead timber, the shrubs which are to afford shade must be planted in the intervals between the vanilla-plants. In addition to these means of shelter the plantation must be surrounded with a hedge of shrubbery for the sake of breaking the force of the winds.

Experience has shown that a vanilla plantation should not be worked for over seven years; but in the mean time a new one is got in readiness, so that there may be no interruption.

 

The vanilla harvest in Réunion occurs from May to August; in Mexico it takes place in December. The fruits, improperly called pods, are best when they have had good exposure to the sun, are fully mature, but not open, and gathered in a hot, dry season.

The modes of preparation differ according to locality, but in general they may be classed under three heads. The oldest method is that of alternately exposing the fruits to the sun and then keeping them in shade till they are sufficiently dry. This is the practice in Mexico and Guiana, where vanilla of excellent quality is produced. Sometimes they are exposed to the action of artificial heat to hasten the drying. Another mode consists in employing boiling water, in which the fruit is dipped for a while, and then treated with sunlight and shade as above. Finally, the third method consists in employing an oven at the temperature of 50° to 75° Cent.; in this the beans are heated from twenty-four to thirty-six hours. Among the many processes, M. Delteil appears to give the preference to that in use in Réunion, i. e., that which employs boiling water, together with the subsequent treatment. Excellent results are also obtained by spreading the fruit on black cloths and exposing them to the heat of the sun.

Finally, the fruit is sent to the drying-room. Here it remains for about a month, being looked after from time to time. The vanilla is then packed in tin cases to prevent its becoming too dry, which would impair its value.

 

CHLORAL AND OTHER NARCOTICS.
By Dr. BENJAMIN W. RICHARDSON, F. R. S.
II.

IT may be interesting at this point to particularize the character of the influence exercised on life by certain of the agents we have now under consideration. With the action of alcohol and tobacco we are all so familiar it is not necessary to repeat what is known of them as