346 Sir Boverton Redwood [June 7, 



sense that they readily lend themselves to conversion, by dissociation, 

 or " cracking," as it is termed, into other compounds of carbon and 

 hydrogen, of lower boiling-point or higher volatility, which are so 

 largely in demand at the present time in the form of motor-spirit. 

 The conversion occurs when the oil is distilled under pressure or is 

 brought into contact with highly-heated surfaces. The chemical 

 changes which occur in these circumstances and the constitution of 

 the products were investigated by Thorpe and Young many years 

 ago. In 1888, I was privileged to be associated with the Fullerian 

 Professor in experimental work which involved the construction of 

 suitable apparatus for carrying out the process on a practical scale, 

 and it was found that in order to obtain the best results it was 

 necessary to effect the condensation of the vapour also under pressure. 

 The process devised at that time is essentially the same as that which 

 is now very largely carried out in the United States, w4th the object 

 of augmenting the inadequate supplies of motor-spirit normally 

 obtainable from the crude oil by fractional distillation. By carrying 

 this treatment further it is possible to obtain aromatic hydrocarbons, 

 and I have on the lecture-table specimens of the high explosive 

 trinitrotoluene, or T.N.T., as well as benzene nnd dye-products, thus 

 obtained from petroleum containing no aromatic hydrocarbons. 



The refining of petroleum, briefly described, consists in the 

 classification of the hydrocarbons, by means of fractional distillation, 

 into the various commercial products, including motor-spirit, lamp- 

 oil, heavy fuel-oil, lubricating oils of various grades, and solid paraifin, 

 and the subsequent purification of these products. The simplest 

 form of fractionating apparatus comprises a still, of which a model is 

 on the table, and a condenser consisting of piping, which may be 

 coiled or straight. Of such an arrangement a photograph (Fig. 6) 

 is now projected on the screen. It represents what is probably the 

 most primitive petroleum refinery in the world, situated at Sherkat, in 

 Mesopotamia, near the Tigris. The stills and condensers are plainly 

 shown, and here again we see, in the foreground, the ubiquitous 

 American kerosene can. 



This model represents a petroleum refinery of modern type, with 

 dephlegmators interposed between the stills and the condensers, to 

 effect the separation of the more readily condensable hydrocarbons. 



In the early years of the industry petroleum products were largely 

 stored, and wholly distributed, in barrels and tin cases, but the system 

 now universally adopted is that of storage and transport in bulk. 

 The type of tank employed for the storage of the oil is shown by 

 the model. These tanks are constructed of steel plates, and are 

 often as much as 1)0 to 100 feet in diameter by 30 to 40 feet in 

 height. The largest holds about 2,00(1,000 gallons. For the trans- 

 port of the oil specially constructed tank steamers, which unfortunately 

 are the objects of unwelcome attention on the part of the enemy's 

 submarines, are used. These vessels, of one of which a sectional 



