80 Mr Rose on the Composition of 



ceived to be distinct at distances much less than half an inch ; 

 but if the points be situated elsewhere, as on the back of the 

 hand, then, although they be distant from each other half an 

 inch, they will scarcely be felt as distinct, provided the line 

 joining them is parallel to the long axis of the part ; when it is 

 transverse, the perception is much clearer, and continues at 

 much smaller distances. 



The discovery, that two equidistant points of contact on the 

 same surface, excite very different ideas of the distance between 

 them, according as the space lies lengthways on or across the 

 limb, is one of the most striking and important which Weber 

 has made, and can be most readily verified by experiment. 



Nor am I aware that modern physiologists have obtained any 

 results more curious than those relating to the different tactile 

 acuteness enjoyed by different parts of the skin ; a difference so 

 great, that the points of a compass applied to the tip of the 

 tongue, can be felt to be distant, when only distant half a line 

 from each other ; whereas, to use Weber's own words, " In me- 

 dio brachio, in medio femore, in dorso scapulae, aliisque in locis 

 sensusille naturatam parum acutus est, ut apices circini 1^ pol- 

 licibus Paris, a se invicem distantes, unam impressionem pro- 

 ferant, si nimirum ita ad has partes admoventur, ut linea utrum- 

 que apicem inter se conjungens secundum longitudinem brachii 

 vel femoris posita sit," 



Oil the Composition of the Water of the Lake Elton in Asiatic 

 Russia, compared with the Water of the Ocean and with that 

 of the Caspian sea. By Mr H. Rose.* 



The Lake Elton, in the Steppe to the east of the Volga, two 

 hundred miles to the south of Saratof is, on account of its extent, 

 the most important of the salt lakes in the neighbourhood of the 

 Caspian Sea. The quantity of the salt of commerce which is 

 procured from it, is supposed to amount to nearly two-thirds of 

 the whole quantity consumed in Russia. The lake is of an 

 elongated form ; the greater diameter stretches from east to 

 west to the extent of about thirteen miles ; the smaller, from 



• Annalen der Physik, 1835. 



