258 ANNUAL REPOET SMITHSONIAN INSTITUTION, 1908. 



It has led also to the discovery of a number of other useful applica- 

 tions of cellulose, of which I will mention only the preparation by 

 various methods of new artificial textile fibers analogous to silk. 



Wood can be worked chemically, however, in another way than 

 by the separation of its content of cellulose. I refer to the process 

 of dry distillation. The very primitive preparation of carbon and 

 wood tar of the old days has developed during the last forty years 

 into the very highly perfected art of wood distillation, which has 

 obtained most important commercial results with decomposition 

 products formerly entirely neglected — methyl alcohol, acetone, and 

 acetic acid. The attempts, first without result, but later crowned 

 with success, to free the ligneous acetic acid from the empyreumatic 

 bodies obtained with it have resulted in the fact that the greater 

 parts of our demands for acetic acid are now supplied by the dis- 

 tillation of wood. This industry received a still further impetus 

 in 1890 by the introduction of a process for the preparation from 

 methyl alcohol of formaldehyde, the production of which has enor- 

 mously extended since the extraordinary variety of uses to which 

 this new product can be put has been recognized. 



Another remarkable method for the treatment of w^ood, fusing 

 it with alkali for the production of oxalic acid, has not developed, 

 but rather has diminished, in importance during the forty years 

 under consideration. It has been replaced by the synthetic method 

 of preparing this acid, as well as of formic acid, by means of carbon 

 monoxide contained in generator gases. Formic acid can be pre- 

 pared so advantageously in this way that it is competing with acetic 

 acid in many of its ap^Dlications. 



The commercial utilization of hydrocarbons of the methane series 

 is brought out in two industries — the distillation of lignites and the 

 refining of petroleum. Both of these industries have shown an ex- 

 traordinary increase in their extent and have displayed numerous 

 marked improvements in their production. Among the latter the 

 desulj^hurization of fetid petroleum of the Ohio type by distillation 

 over copper oxide should be considered a technical achievement of 

 high rank. 



The development of coal distillation and the treatment of tar 

 affords a particularly important and interesting example of prog- 

 ress. When this society was founded only one form of distillation of 

 coal was- recognized — its application to the manufacture of illvmii- 

 nating gas, which dates from the end of the eighteenth century. 

 This distillation was carried on at a low temperature and furnished 

 the entire amount of tar produced, the tar which is so important 

 in the recently developed color industry. In 1880 the output of tar 

 began to be less abundant, a fact caused not only by the constant 

 increase in its use in the production of tar dyes, but also to a great 



