8 GEOLOGICAL MEMOIRS. 



Bryozoa are found to increase, the Foraminifem to diminish, in 

 specific diversity ; (2) Bryozoa are scarce in deposits of plastic clay 

 (*•' Tegel ") and unmixed sand ; (3) a fauna rich in Bryozoa may 

 be regarded as proving that the deposits containing it were formed 

 in a moderately deep sea. [Count M.] 



On the Azote and Organic Matters in the Crttst of the Globe. 

 By A. Delesse, For. Mem. G. S. 



[Eecherches de I'Azote et des Matieres Organiques dans I'Ecorce Terrestre. 

 Annales des Mines, 5"'« ser. vol. xviii. 4^ livr. et 5'^ livr. de 1860, pp. 151-323 ; 

 and published separately, 1861.] 



This memoir is especially devoted to the consideration of the 

 amount of azote contained in various minerals and rocks, existing in 

 them in such a state as to be given oif as ammonia, either when they 

 are heated alone or with a mixture of caustic soda and lime. In 

 very many cases there can be no doubt of this azote having been 

 defived from organic bodies; but, when the author makes use of the 

 term organic matter, it must be borne in mind that, strictly speaking, 

 he refers to compounds containing carbon and nitrogen, such as 

 chemists usually term organic, without thus being necessarily derived 

 from animals or plants. 



The memoir commences with an introduction in which are pointed 

 out the precautions necessary to avoid errors, and how it is needful 

 to experiment on materials which cannot have been contaminated by 

 foreign bodies, or acted on by the atmosphere. Though, when rocks 

 contain a very small amount of azote, they may be influenced by the 

 organic matter introduced by the infiltration of water from the sur- 

 face, yet it is shown that in many cases, instead of there being any 

 increase due to this agency, the action of the atmosphere does in 

 reality diminish the amount of azote naturally existing in the rock 

 at a greater depth.' After describing the nature of the products 

 evolved by the distillation of minerals and rocks, the author points 

 out that their alkaline character is no safe criterion of the 

 amount of ammonia given off, since it may be entirely masked 

 by acids also evolved during the operation. Recourse was therefore 

 had to the process usually employed in determining the nitrogen in 

 organic bodies, viz, heating the finely powdered substance with a 

 mixture of caustic soda and lime, in a glass tube, receiving the 

 products in a knoAvn quantity of sulphuric acid, and determining the 

 amount of ammonia by ascertaining the quantity of a standard solu- 

 tion of saccharate of lime required to neutralize the excess of sul- 

 phuric acid. Sufficient material was used to enable the author to 

 approximately determine the amount of azote to the xo"T7,Vou^^ P^^^ 

 of the substance analysed, as shown in a series of tables, in which the 

 quantity is expressed in thousandths or decimals of thousandths, as 

 is also the case in those quoted in the following summary. 



He next considers the amount of azote in various animal products 

 in a recent and fossil state, and shows that, though local circumstances 

 have so much influence that one cannot with perfect certainty judge 



