Intelligence and Miscellaneoits Articles, 553 



mens, diflFer from the per-centage proportions required by the for- 

 mula in precisely the same particulars. 



I heartily agree with Mr. Mallet in the opinion he expresses in 

 his concluding sentence, that it is far from " desirable to add to the 

 already numerous names of stilbite-like minerals ; " and the sincerity 

 of his expressed opinion is most strikingly evinced by his refraining 

 from naming the substance till time should have tested its specifijc 

 individuality. 



P.S. For the sake of comparison with Mr. Mallet's description, 

 I quote from a paper (which I have just laid my hands upon) on the 

 Geology and Mineralogy of Skye, read some years ago at the Edin- 

 burgh Geological Society. Speaking of the minerals to be found at 

 the Storr, " Laumonite is here found in veins of about 1 inch in 

 thickness, which consist of a congeries of minute crystals, so con- 

 fused as to have a granular appearance ; this mineral, strange to say, 

 used to pass under the name of hypostilbite, and under that name 

 came into Dr. Scott's hands, who analysed it." 



To the Editors of the Philosophical Magazine and Journal. 

 Gentlemen, 



I believe the great question at issue between M. Riess and my- 

 self is the exactitude of a law of " electrical heat " which M. Riess 

 thinks he has discovered. Now, without seeking to prolong a 

 painful controversy, or further canvas the accuracy of the several 

 statements relative to myself found in M. Riess's last communica- 

 tion, I trust you will be so good as to grant me the privilege of a 

 few lines immediately bearing upon the law of electrical heat just 

 referred to. 



The course of experimental research pursued by M. Riess amounts 

 to this : — He accumulates and discharges through a wire a given 

 quantity of electricity. First the given quantity is collected on a 

 certain number of coated jars, then on a larger number. He says, 

 that in the latter case the tension or intensity (or whatever he may 

 please to call it) of the accumulated charge has suffered a change, 

 and that in consequence of this change the heating power is dimi- 

 nished ; that the heat is in fact inversely proportional to the surface 

 over which the electricity has been expanded, all other things being 

 the same. 



I take occasion, in opposition to all this, to remind M. Riess of 

 some well-known phsenomena of electrometer indications, and cer- 

 tain generally admitted laws of electrical force and measurement by- 

 such instruments. I show, and I believe very clearly, that these 

 instruments signalize nothing whatever of any change in quality of 

 the accumulated charge ; that they are altogether influenced by 

 conditions quite foreign to all such views ; that what we learn from 



Phil Mag. S. 4. No. 82. Buppl VoL 12. 2 



