PRESIDEN?’S ADDRESS. 49 
soils. Lately a great deal of attention has been given to 
this subject; but it is by no means a new one, for Professor 
Delesse published in the Ann. des Mines in 1860 a long 
investigation upon the occurrence of nitrogen and organic 
matters in rocks, entitled ‘De lazéte et des matiéres 
organiques dans l’écorce terrestre.” 
In this he gives the amount of nitrogen obtained from 
104 varieties of crystalline and sedimentary rocks from 
different parts of Europe, including various calcareous 
rocks, grits, sandstones, marl, and alluvial soils. 
They all yielded nitrogen ; most of them gave ammoniacal, 
but others acid, products on distillation. Some gave acid 
products at first, followed by alkaline ones, and a tarry 
odour. The nitrogen was, doubtless in many cases, present 
as organic compounds, 
Some years ago, 1873-4, I examined a large number of 
minerals and rocks for ‘organic matter,” and found that 
rock-crystal, amethyst, topaz, and many other minerals 
eave off gases and ammoniacal empyreumatic distillates, but 
the investigation had to be laid aside, and the results have 
not yet been published. 
Hugo Erdmann (Ber., 1896, 29) has also found that a. 
number of minerals which occur in ancient igneous rocks 
evolve ammonia when warmed with pure soda solution, and 
he has estimated the amounts; thus a mineral resembling 
polycrase gave °028 per cent. of nitrogen evolved as, 
ammonia. Another mineral resembling euxenite contains. 
‘005 per cent. of nitrogen. He states that many other 
minerals from the north of Europe also contain nitrogen, 
such as ytterspar, euxenite, fergusonite, gadolinite, and 
eschynite. Professors Ramsay and Tilden, working inde- 
pendently, however, did not find nitrogen in most of the 
minerals examined by them. 
It was known that hydrocarbons, carbon monoxide, 
carbon dioxide (in both the liquid and gaseous states), 
nitrogen, and other gases occurred in rocks, but they found 
D 
