368 Notices respecting New Books. 



Dr. Lunge, in his Introduction, notices the enormous reduction 

 in the prices of coal-tar and its various products which has taken 

 place since 1883. At that time coal-tar fetched at the gas-works 

 55s. and pitch 33s. to 35s. per ton, benzol, of 90-per-cent., was 

 worth 3s. ; whereas in 1885 tar had fallen to 12s., and in 1886 to 

 7s. and 90-per-cent. benzol to Is. 8d. per gallon. According to 

 the, ' Journal of Gas-lighting,' tar, on August 27, 1887, was 10s. to 

 15s. per ton, and benzol, of 90-per-cent. 2s. lOd. per gallon; and 

 this in spite of the fact that the great gas-companies are burning 

 large quantities of their tar ! It is not difficult to see the cause of 

 this depreciation. It arises from the fact that the tar produced in 

 Europe is more than is required by the makers of aniline colours 

 and other tar products. The demand is not equal to the supply. 

 The Introduction also contains much interesting matter, in the form 

 of Historical Notes and Statistics, which we commend to the notice 

 of all who are interested in the coal-tar industry. 



As regards the various processes for obtaining coal-tar, the 

 working of coke-ovens, the preparation of benzene from the various 

 tars, including that obtained by subjecting petroleum to high tem- 

 peratures, the work contains the fullest information, including 

 diagrams of the ovens and other appliances, and lists of the patents 

 bearing on the subject. 



Chapter III., on "The Properties of Coal-tar and its Consti- 

 tuents," is not only very interesting, but contains more information 

 in proportion to its length (60 pages) than in any other work we 

 have seen. 



The question of burning tar as fuel, now so much agitating gas- 

 companies, is treated fully, and excellent illustrations are given of 

 the apparatus best adapted for the purpose. 



Chapter V. is on " The First Distillation of Coal-tar," and is 

 treated with a fullness and clearness which leaves nothing to be 

 desired. 



Chapter VI. is on " Pitch," and in it we have instructions for 

 the testing of the various qualities. We do not remember to have 

 seen these methods in print previously. 



Chapter VII. is on " Anthracene Oil." All the best methods of 

 extracting the anthracene and testing it for its purity are given. 

 The illustrations of filter-presses, washing-apparatus, &c. are excel- 

 lent. The only part of this section which leaves anything to be 

 desired is the estimation of the quantity of anthracene in tar. 

 Unfortunately no thoroughly reliable mode of doing this has, so far 

 as we know, yet been made public. 



Chapter VIII. is on " Creosote Oil." This section is very com- 

 plete. The various processes which have been devised for decom- 

 posing the oil by heat, so as to obtain more valuable products, are 

 described and illustrated. The attempts to utilize creosote oil for 

 lighting are described, and diagrams of the apparatus devised by 

 Hartmann and Lucke, and Lyle and Hannay are given. The sec- 

 tion on the " Employment of Creosote Oil for Pickling Timber " 



