1821.] Scientific Intelligence. 315 



the water escapes by capillary movement through the- pores of 

 the salt till what he supposed to be the neutral state be acquired, 

 when the salt becomes compact and insoluble. When any mal- 

 formation of the nucleus produces a cavity or partial vacuum m 

 the interior of a crystal, then the capillary attraction may be 

 exerted to that cavity as well as to the surface ; but that this is 

 modified by various accidental circumstances. By pouring hot 

 water upon a crack in the mouth of a bottle, about three inches 

 in length, it extended to five inches, but returned again when he 

 stopped adding the hot water ; cracks in pieces of window glass 

 were, also, extended by pressure, and contracted again upon its 

 removal : hence Mr. Deuchar concludes, " that water may enter 

 the void interstices of crystals, when aided by pressure, not only 

 from the porous nature of their particles, but also from their tem- 

 porary display of rents during the application of a high temper- 



The paper concludes with a number of observations upon the 

 porous nature of glass to water as well as light. Ihis he thinks, 

 is proved by the experiments with empty bottles, well closed at 

 the mouth, which have often been sunk in the ocean, and brought 

 up full of water. In one, performed by Mr. Perkins, "the cover- 

 ings were taken off layer after layer, but no signs of moisture 

 were visible ; " yet the bottle was full of water. In one experi- 

 ment, by Mr. Grant, an empty bottle secured with a cork, wax, 

 layers of oil cloth, &c. came up full of salt water ; and in another 

 experiment, a bottle with fresh water, similarly secured, came 

 up filled with salt water : in both the layers of oil cloth, &c. were 

 dry, and the cork, when cut across, presented no change. 



Article XVI. 



SCIENTIFIC INTELLIGENCE, AND NOTICES OF SUBJECTS 

 CONNECTED WITH SCIENCE. 



I. Oil obtained by Distillation from the Hop. 



(To the Editor of the Annals of Philosophy.) 

 BIR Stpt.il, 1821. 



In Dr. Ives's communication on the Properties of the common Hop 

 (Annals of Philosophy for March), I was surprised to observe it 

 asserted, " that no essential oil can be obtained by distillation In any 

 portion of the hop," having, in the course of experiment, obtained a 

 considerable quantity ; the only difference being in the quantity ot hops 

 submitted to distillation, six or ten pounds, instead of as many ounces, 

 in the case of Dr. Ive6. . ., . 



In the kiln-drying of hops for sale, a portion of the essential oil is 



