Miscellaneous Intelligence. 243 



These substances, having a tendency to combine, would go to 

 form a corresponding amount of carbonate of ammonium. 



Dr. Natterer is inclined to assign the chief part in the forma- 

 tion of not only the partly clayey, partly stony deposits on the 

 sea-bottom, but also of calcareous and siliceous structures in liv- 

 ing organisms to precipitates caused by the dissolved carbonate 

 of ammonium. That the mechanical deposition of detritus car- 

 ried to sea in suspension by surf or by river-waters plays only a 

 subordinate part in comparison with such chemical precipitates 

 (of carbonate of lime, siliceous clay, free silica, etc.), appears 

 especially from the fact that, except near the mouths of rivers, 

 clear water, free from suspended matter, was obtained directly 

 from the water-bottles at all depths in the Eastern Mediterranean; 

 and Dr. Natterer accordingly expresses the view that in the 

 Porcupine and Shearwater expeditions in 1 8*70—71, it was only 

 because the Sigsbee apparatus was allowed to touch the bottom 

 that fine mud was found in suspension in samples from the lowest 

 layers of water. 



The late Dr. W. B. Carpenter, who had scienti6c charge of 

 those expeditions, ascribes the presence of suspended mineral 

 particles to the fine sand brought down by the Rhone and other 

 rivers (see Proceedings R. S., xix, p. 146, and xx, p. 535). The 

 relatively slight importance of the action of mechanical deposi- 

 tion is further shown by the circumstance that where the chemi- 

 cal conditions necessary for precipitation are absent, mineral 

 particles are dissolved by the sea-water, except when they are 

 j)resent in sufficient quantity to cause the continued reactions 

 observed by Natterer. In fact, the examination of water samples 

 collected at the Tanitic mouth of the Nile, and near the harbor 

 of Port Said, towards which all Nile water is carried by an 

 easterly current, after it reaches the sea showed a surprisingly 

 small amount of suspended matter even in late summer, when the 

 quantity is likely to be large on account of the tropical cloud- 

 bursts. Natterer supposes that the fine sand brought down by 

 rivers is only to a small extent deposited directly, but that for 

 the most part it is first dissolved, and remains in solution until a 

 current carries it to a part of the sea where new conditions bring 

 the separating action into play, and precipitation is caused by 

 the action of living or dead organisms. This process assists in 

 the formation of coral reefs and banks, helps the tide and the 

 surf in the building of dunes, and provides materials for the 

 mineral parts of organisms living in the sea. 



Where the sinking of decaying organisms is prevented by a 

 strong current, Natterer supposes that a strong crust is formed 

 on the bottom, instead of the muddy deposits which cover by far 

 the greater part of the Mediterranean basin ; and this crust is 

 harder the more slowly it is formed. Samples brought to Vienna 

 prove the existence of intermediate transition stages between the 

 two, and it is suggested that the ammonia, formed by the oxida- 

 tion of the lower layers of deposits containing decaying organ- 

 isms in the manner already described, rises to the actual sea- 



