40 THE IRON ORE DISTRICT OF EAST TEXAS. 



in length, about thirty inches in width and twelve inches in height. The re^ 

 torts are filled from the front, each being supplied with a movable iron cover. 

 All the retorts are placed in one furnace and heated at the same time through 

 cross fires. The vapors as they distill are conducted into a collecting main, 

 which is connected with the back of each retort by smaller pipes and elbows. 



This system has its disadvantages, as at each filling the resulting coke has 

 to be removed and the retorts have to be shut off during the operation from 

 the collecting main, causing an interruption in the process. 



A very ingenious apparatus, allowing the continuous manufacture of the 

 tar, consists of a number of vertical cylinders of cast iron or chamotte mass. 

 These cylinders,, from twelve to sixteen feet high and nearly three feet in 

 diameter, contain a system of rings with oblique walls (bell shaped). These 

 rings are placed one over another vertically, so as to form a second interior 

 cylinder, which is covered with an iron cone, over which the filling of the ap- 

 paratus takes place. The exterior and interior cylindrical chambers formed 

 by this system of rings are connected through spaces left between the walls 

 of the rings. The apparatus terminates below in a cone communicating 

 through its lower aperture with a box, which can be fchut off from the cylin- 

 der. After filling, the coal gradually sinks between cylinder and ring walls. 

 Flues passing around the cylinders furnish the heat necessary for distillation. 

 The vapors of the distilling coal enter between the rings into the interior cyl- 

 indrical chamber, from which they escape into the collecting and condensing 

 apparatus. On opening the lower cone the ashes fall into the box beneath. 

 The ashes are removed every two hours. 



Notwithstanding the advantages that thi& process offers are very great, the 

 distillation of the coal in retorts is still preferred by a number of manufac- 

 turers for various reasons which, however, can not be mentioned here. After 

 distillation the tar is refined and rectified, and its further treatment depends 

 on the qualities it possesses and the various products of manufacture for which 

 it is to be worked. 



The many varieties of tar obtained differ but little in external appearance. 

 If the process of manufacture was well conducted they possess a light coffee- 

 brown color, solidify on cooling on account of their parafBne contents, are of 

 alkaline reaction, rarely acid or neutral, and of a strong odor, resembling that 

 of creosote. Exposed to the air, they oxidize and assume a dark brown, some- 

 times deep black, color, their specific gravity varying between .880 and .975 

 (water 1.000). 



PARAFFINE. 

 One of the products resulting from the dry distillation of brown coal is 

 paraffine, the obtaining of which was the main object of the European brown 

 coal industry for many years after the discovery of the possibility of its manu- 



