AND THE COLOUR OF WOODS, 101 



the term was lengthened to a month. But when the wood was exposed 

 to the light, at the end of fifteen days it became of a violet colour. The 

 same results were obtained when hydrogen, carbonic acid, and steam 

 were used — that is to say, darkness produced no effect, but light caused 

 a violet colour to appear ; except that in the case where the last-named 

 agent was employed, the violet was of a more intense hue, owing to the 

 moisture. - With air confined in an hermetically-sealed tube, it took a 

 month to produce any change in the colour, when the wood was kept in 

 darkness. At the end of that time it became a light brown. When ex- 

 posed to the light at the end of fifteen days it became violet, like those 

 described above, but the violet in this case was more red. 



When common atmospheric air was used, the effect produced upon 

 pieces kept severally in darkness for fifteen clays and a month was the 

 same — namely, to produce a light brown hue, but the light caused a 

 brownish red violet to appear. The above experiments on the action of 

 outward agents on the uncoloured woods of amaranth have been tried 

 chiefly on the palo morado and the tananeo. The specimens operated 

 upon were presented to the Chemical Society of Paris on the 18th 

 August, 1857. The following conclusions may evidently be deduced 

 from the above observations : 1. That light affects greatly the develop- 

 ment of the colour of these woods. 2. That water is favourable to that 

 phenomenon, probably, as has been said, in consequence of a physical 

 action. 3. That atmospheric action is insufficient to develope the colour- 

 ing matter, even with the assistance of water. But aided by light, it 

 modifies the violet produced by the action of light alone, and gives it a 

 tendency to become red. I think it expedient to glance at the results of 

 analogous experiments made as to the influence of atmospheric action on 

 the colour of the woods of Quebracho and Taigu. These experiments 

 determined the fact, that although air and light were necessary to the 

 development of the yellowish red colour peculiar to the Quebracho, yet 

 air alone was sufficient to cause the appearance of a yellowish green 

 tinge in the " Taigu." In the case of Amaranth, on the other hand, light 

 seems to take an active part in the production of the purple colour of that 

 wood. Although very limited, these results show us how necessary it is to 

 multiply, repeat, and extend our experiments before laying down general 

 assertions. I have been induced to make these researches from a natural 

 love for these pursuits, and also from a desire for that applause ac- 

 corded to those who discover any one of those laws which we consider as 

 so many conquests gained by intelligence over matter, or beacons which 

 light us over the vast untraversed space which surrounds us. 



Like causes always produce like effects, but like effects may arise 

 from different causes. We are tempted to take the weakness of our un- 

 derstanding for the simplicity of nature. We seek everywhere the 

 original type of existence and unity of action. Nature, it is true, may 

 sometimes follow the beaten track, but its methods and resources are 



