Properties of Rosewood and other Hard Woods. 375 



whether colouring matters or not, are compounds of carbon, 

 hydrogen, and oxygen — nitrogen being absent. Rosewood 

 extract was also found, after testing, not to contain 

 nitrogen. A striking peculiarity of tliis extract is its 

 strong tinctorial power, 1 part in 100,000 parts of alcohol 

 showing a distinct colour in an ordinary test tube. It 

 does not appear to have the qualities of a weak organic 

 acid. It may also be mentioned that this spirit extract 

 gives to paper a colour very much like that produced by 

 nitrate of silver. 



The Sissoo wood differs chiefly in its naphtha extract. 

 The proportion of this is much larger than in any of the 

 other rosewoods examined, and it appears to have some 

 peculiarities requiring further examination. One of these, 

 however, is worthy of particular notice. If, before it is 

 more than a couple of days old, it is dissolved in alcohol, 

 it communicates a deep and splendid purple colour to that 

 liquid. It appears, however, to lose this property very 

 soon, probably by oxidation. 



Two examples of mahogany operated upon gave the 

 following results : — 



Kind of Wood. Treated with E^:tract 



Spanish or Cuba Mahogany, Siciet- i Naphtha, 1-338 per cent. 



enia Mahogani. Specific gravity, < Ether, 2 "843 „ 



•840, ( Alcohol, 12-292 „ 



Honduras or Bay Mahogany. Sioiet- ( Naphtha, 0-864 „ 



enia Mahogani. Specific gravity, < Ether, 0-292 „ 



•420, \ ( Alcohol, 3-145 „ 



A comparison of the tables shows that Spanish 

 mahogany, which was treated in the same manner as the 

 rosewoods, gave nearly the same percentages of the 

 various extracts. But the naphtha extract of mahogany 

 has not the pine resin odour when heated on a spatula, 

 and its ether and alcohol extracts have only a light 

 pinkish colour in the solid state, and have hardly any 

 tinctorial power in solution. The spirit extract has one 

 property remarkably different from any noticed in the 

 alcoholic extract of rosewood. When dry, it is brittle 

 and very friable on being rubbed between the fingers ; but 

 when heated up with turpentine to a temperature nearly at 



