lO TRANSACTIONS OK kOVAI. SCOTTISH ARBORICULTURAL SOCIETY. 



success of the other part of the process owing to the immense 

 amount of hme he had to use in order to free the gases of acid 

 products, including the carbonic acid. Pettenkoffer was able 

 to greatly improve the illuminating power of the wood gas by 

 superheating it, but the introduction of coal gas with its much 

 greater illuminating power at less cost killed any chance of 

 going on with this industry. The industry had, however, got 

 a start, and investigation was pushing forward. According to 

 Klar, a works for wood distillation was started in 1819, at 

 Hausach (Baden), but it did not pay. Later on the discoveries 

 in connection with the manufacture of aniline colours called 

 for products and derivatives of wood distillation such as pure 

 methyl and acetone, and it was only then that the wood dis- 

 tillation business may be said to have been born, in so far as 

 the manufacture and recovery of all its products is concerned. 



Outside of the recovery and utilisation of all the products it 

 is evident that there has always been a demand for charcoal, 

 originally for heating purposes, such as cooking and metal 

 smelting, but with the invention or introduction of gunpowder 

 a new demand sprang up. The charcoal for this purpose should 

 be easily ignited, burn quickly, and leave little ash, and the 

 more cellulose a wood contains the more suitable for gunpowder 

 will be the charcoal. Dogwood and alder are the woods pre- 

 ferred for sporting powder, while for blasting powder birch can 

 be employed. For making certain powders it is preferable 

 that the distillation be not carried to complete carbonisation, 

 but that some of the gases be left in the wood which is then 

 brown instead of black, and is called " Charbon Roux." 



Very exacting regulations were at one time inserted into 

 powder contracts so as to secure uniformity in the analysis and 

 properties of the charcoal employed in its manufacture. The 

 manufacture of charcoal for gunpowder, owing to the use of 

 smokeless powder, has of late fallen off very considerably, and 

 the demand for charcoal for this purpose is consequently now 

 insignificant compared to what it was at one time. 



Another use to which charcoal has been put for many years is 

 in the foundry, where it is used in the form of a wash for painting 

 the moulding sand so as to form a skin between the molten 

 metal and the sand. In preparing charcoal blacking for this 

 l)urpose the nature of the wood again plays an important part, 

 oak producing the best ; but as for some castings blacking made 



