516 EXPERIMENT STATION RECORD. 



Nitrate marls of Egypt {Amcr. Feyt., 1 {1894), N^o. 5, pp. 269-275).— 

 It appcius tVoin Egyptian Nitrate Mission reports tliat the material 

 known as "Marog" and extensively used as a fertilizer in Egypt is "a 

 foliated marl, greenish, and sometimes reddish gray, with veins of white 

 gypsum and incrustations or small crystals of chlorid of sodium and 

 some snlphate of sodium. . . . Its primary stratum has a depth of 

 from 50 to 100 meters, and is horizontally bedded between the Lower 

 Londinian, a hard white limestone of the Lower Eocene, a tertiary 

 formation, and tlie Suessonian, a yellowish or grayish limestone; 

 between the Lower Eocene and the Up]»er Cretaceous formation." Its 

 geological age has not been definitely determined, but it is believed to 

 belong to the Upper Suessonian. 



The deposits crop out along the hills bordering the Nile Valley in 

 Upper Egypt over an area of probably 30,000 square miles, and are 

 believed to be practically inexhaustible. 



When exposed to the air these marls readily crumble to a fine pow- 

 der, although at lower depths they are very hard, tenacious, and strong. 

 If not already abundant, nitrites and nitrates soon appear in consider- 

 able amounts on exposure to the air. As there is believed to be no 

 organic matter i)resent for microorganisms to work on, it is claimed 

 that we have here an interesting and novel illustration of nitrification 

 without the interference of organic matter. A suggested explanation 

 of this phenomenon is "that the chlorid of sodium in the rock is dis- 

 solved by the humidity of winter or of high Nile, and is drawn out by 

 capillarity and by dry air acting as a pneumatic machine. This chlorid 

 of sodium is decomposed and decomposes the water. The oxygen of 

 the water combines with the nitrogen of the air to form nitrous, and 

 afterwards nitric, acid. This combines with the sodium to form sodium 

 nitrate. The chlorid of ammonia which is also formed is volatilized." 



The analyses reported show the better quality of these marls to con- 

 tain from 8.82 to 11.77 per cent of nitrogen calculated as nitric acid. 

 Many which are of poor quality when first exposed become rich in a 

 comparatively short time. Experiments looking to the extraction and 

 purification of the nitrate for the market are briefly alluded to. 



Phosphate deposits of Algeria, C. T. Grellet {U.S. Consular 

 Bpt. 1894, Nov., pp. 365-367). — The existence of large deposits of phos- 

 phate in the western part of Tunisia has been known since 188G. 

 Within the last two years similar deposits have been discovered in the 

 Department of Constantine (eastern Algeria), in the Djebel Dyr, in the 

 Djebel Koiiif, and at Kissa, in the region of Tebessa, about 155 miles 

 south of Bone. The Tebessa deposits cover several hundred square 

 miles and are said to be almost inexhaustible. The phosphate, com- 

 posed cheifly of bones and teeth of sharks, " is found in a semipulver- 

 ulent state in strata from 0.5 meter (20 in.) to 3 meters (10 ft.) thick, 

 intercalated in white marl and siliceous limestone. Its grade aver- 



