124 ON A PROCESS OF FRACTIONAL CONDENSATION. 



Of the New Process. 



The chief distinctive feature of my process, as compared with the common one, 

 consists in this, — that the operator has complete and easy control of the temperature 

 of the vapors given off in distillation ; and consequently can readily cool these vapors 

 to the lowest limit of temperature which the most volatile portion, under the circum- 

 stances, is able to bear and retain its vaporous condition. It will be seen at a glance 

 that, under these conditions, the operator has it in his power to secure in any case 

 the very largest possible amount of condensation of the heavier from the lighter 

 vapors. The liquids resulting from the condensation of the less volatile portions of 

 course fall back into the retort, while the vapors of the more volatile parts continue 

 to go forward to a cold condenser, descending in the opposite direction, from which 

 the condensed product falls into a special receiver. In this manner he is able to 

 obtain, in each successive operation, a series of products which shall contain the 

 minimum quantity of the less volatile constituents, which a single distillation is capa- 



ble of affording. 



Of the common process, on the contrary, nearly the reverse of all this is true : the 

 operator having no control whatever ; being forced to receive the vapors at the tem- 

 perature which they naturally acquire in passing from the retort, and laden with such 

 proportion of the less volatile bodies as may be carried forward with them* 



apparatus 



In one of the older 



own, is that employed in the rectification of alcoholic spirits, on a manufacturing scale, 

 forms of this apparatus, that of Solimani, to which my attention was first called by a friend, after my process 

 had been in use more than a twelvemonth, the temperature of a dephlegmator is kept within such limits as to 

 give alcohol of any required strength more readily than by the common methods. The mode of construction of 

 this apparatus is, however, only adapted to manufacturing purposes, and it could not be utilized in the more 

 exact experiments required in scientific research. Either on account of its complication, or some other cause, 

 the apparatus of Solimani has, I believe, long since been abandoned. 



that " the boiling-point of 



(Quarterly 



[Or 



that 



cation which are practised by distillers in the manufacture of alcoholic spirits, are applicable to the separation 

 of benzole from the less volatile fluids of naphtha " ; and, appended to his scientific treatise on coal-tar, under 

 the title « Of a Practical Mode of Preparing Benzole? goes on to describe a process for that purpose, which 

 I believe, he had previously patented. It appears that Mansfield did not employ this process in his research, 

 but obtained his benzole, as well as the other less volatile hydrocarbons, in the usual manner, — by simple 

 distillation. 



In the belief that no process of fractioning at all analogous to mine has ever been employed in scientific 

 research, and that I am not in any way directly indebted to any of the devices of my predecessors, I have 

 taken no special pains to consider these devices in much detail. I may say, however, that I have found no 



