646 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 readi- 

 ness, so that there may be no interruption. 



The vanilla harvest in Reunion 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 gen- 

 eral 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 Reunion, i. e., 

 that which employs boiling water, together with the subsequent treat- 

 ment. 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. KICHABDSON, F. K. 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 



