Dr Reichenbach on Petroletim or Mtneral-otL 381 



Amiano, and that made artificially. The boiling point of tur- 

 pentine-oil is from 158° to 160° C, that of Persian naphtha accor- 

 ding to Thomson is 160°, and that of artificial petroleum is 167° 

 C. ; variations which in mixed substances can hardly be taken into 

 account. During distillation the boiling point of both becomes 

 higher, owing to the partial separation of the component parts. 

 All are volatile in the air in nearly the same degree if they are 

 rectified. They make a gi'easy mark on paper which afterwards 

 disappears. All these oils ^re distinguished by the soot formed 

 when they are in combustion. They all dissolve sulphur in a 

 similar manner. The property of turpentine oil observed by 

 Davy of extracting iodine from iodine water, is also possessed in 

 a most complete manner by petroleum. Not one of them is solu- 

 ble in water, but all give it the peculiar odour. When mixed 

 with concentrated sulphuric acid, they "acquire a brown tint ; 

 but in all of them a colourless portion is separated when the mix- 

 ture is not disturbed. Potassium disengages in all some bubbles, 

 then turns tranquil, remains metallic, and the brownish-yellow 

 matter is formed. The last mentioned effect, and the disengage- 

 ment of the bubbles, are more distinct in turpentine-oil. In spirit 

 of wine they all shew the same solubility. Caoutchouc swells out 

 in a remarkable manner in all, but is not dissolved in the cold. 

 All three appear to be compounds, or probably mixtures, of se- 

 veral substances, which may to a certain extent be separated by 

 distillation. Hence arise the discrepancies in the analyses of 

 Saussure, Thomson, Opperman, &c. The oxygen, as one of the 

 ultimate component parts, is awanting in all of them, or at least in 

 the older analyses. The opposite opinions of Saussure and Op- 

 perman upon this point are probably both correct, but each for 

 a distinct substance. But here it is sufficient to know that there 

 are certain turpentine oils which are quite as free as petroleum 

 from oxygen. 



This comparison of their most important relations is sufficient 

 to point out the resemblance of these oils, and to give room for 

 the conjecture that their principal component parts are iden- 

 tical. When we remember that coal is so filled with remains of 

 plants that its origin has been attributed entirely to the destroy- 

 ed vegetables of an early period, it must appear probable that 

 petroleum was formed from such plants as affiarded these oils, 

 and in one word, that our mineral-oil is nothing but the turpen- 



VOL. XVI. NO. XXXII.— ATEIL 1634. CC 



