1820.] Scientific Intelligence. 307 



As to the truth of the assertion that these concretions were 

 actually taken out of the urinary bladder of a dog, there seems 

 to me to be some room for scepticism. The gentleman who 

 presented the concretions to the museum is a man of the highest 

 respectability, and he himself firmly believed the truth of the 

 statement which he gave. He must, therefore, have entertained 

 a favourable opinion of the veracity of the person from whom he 

 received them. There is no doubt a possibility that he may have 

 been imposed upon ; though for what purpose such a deception 

 could have been practised, in a case where neither profit nor 

 credit could redound from it, and where the person practising it 

 did not even seem to have been aware that such concretions 

 were extraordinary, it is difficult to conceive. 



The thing seemed to me at least of sufficient importance to 

 deserve to be recorded. It may serve to draw the attention 

 of others to such concretions, if they should ever again occur, 

 III. Naphtha from Persia. 



Mineralogists and chemists are aware of the existence of 

 naphtha in Persia, and of the many wonderful stories that have 

 been related of its volatility and combustibility. I have been 

 lately favoured, through the kindness of a gentleman who has 

 spent many years in the neighbourhood of Persia, with a speci- 

 men of the naphtha in the purest state in which it occurs. It is 

 colourless as water, has the specific gravity 0-753, and precisely 

 the same smell and taste as the naphtha which is made in this 

 country from the distillation of coal. Indeed our artificial 

 naphtha and the Persian naphtha resemble each other in all 

 their chemical properties as far as I have compared them toge- 

 ther. I have never got any naphtha made in this country from 

 coal quite so light as the Persian. The specific gravity of the 

 lowest which 1 have met with was 0-817, but probably had it 

 been rectified once or twice more, it would have become as 

 light as the Persian. 



The statements respecting the extreme volatility of naphtha 

 have not been confirmed by my experiments. The Persian 

 naphtha boils when heated to 320°. If we continue the boiling, 

 the naphtha becomes darker coloured, and the temperature may- 

 be made to rise as high as 338°, and perhaps even higher. Indeed 

 in a silver vessel I raised its temperature to 352°. The same 

 increase of temperature takes place when oil of tuqientine is 

 kept boilino-. There are two consequences which may be drawn 

 from these facts ; and one or other of them must be the true 

 one. Either naphtha and oil of turpentine are composed of two 

 distinct hquids differing in their volatihty ; or they are partially 

 decomposed at the boiling temperature. From the increase of 

 colour which takes place when naphtha is boiled, one would h,e 

 disposed to adopt the second of the two alternatives. 



When a grain of Persian naphtha is decomposed in the usual 

 way by means of pero.x.ide of copper, we obtain 1-35 grain of 



u 2 . 



