318 SECTIONAL TRANSACTIONS.— B. 



It was privately suggested by Dr. Franklia that the substance GeCljCNHj might 

 in reality be a mixture of Ge(NH).2 with NH4CI. This view is supported by the fact 

 that the substance has a very small ammonia pressure at ordinary temperatures. 

 The addition of ammonia also confirms it. NHjCl is known to add three molecules 

 NH3, forming a compound of dissociation pressure, variously given but in the 

 neighbourhood of 1,040 mm. at Oil, per cent. This is the dissociation pressure of 

 GeClilGNHa. A mixture of Ge(NH)2 with 4NH4CI should take up 12 molecules of 

 NH3 against the 10 molecules found. It is suggested that the Ge(NH)2 acts for this 

 purpose like 2 molecules NH3. 



From the substance GeCl46NH3 the imide was isolated by dissolving out the 

 NH4CI with liquid NH3. Owing to the extremely hygroscopic nature of the imide 

 it was difficult to obtain a pure specimen. By carrying out the preparation and the 

 weighing for analysis in an enclosed vessel a fairly pure specimen was finally obtained. 



The action of heat and of the gas on the mixture of germanium imide and 

 ammonium chloride has been investigated. 



Alkyl substituted imides have also been obtained by the action of primary and 

 secondary amines on germanium chloride. Tertiary amines do not react with this 

 substance. 



From the products of the hydrolysis of the substituted imides thus obtained it is 



yNH _ 



concluded that the structure of germanium imide is Gef^ andnotNrirGe— NH2. 



"^NH 



Prof. J. Smeath Thomas. — Recently discovered Nitrate Deposits in South- 

 west Africa. 



The deposit referred to in this communication occurs in the Gibeon district of 

 S.W. Africa. The geology of the arid area lying to the east of the railway from 

 Keetmanshoop to Marienthal is briefly as follows. On the Upper Dwyka deposits 

 rests a layer of roughly 500 feet in thickness of Ekka shale mixed with some limestone, 

 and this in turn is covered by a band of hard calcareous rock containing quartz pebbles 

 varying in thickness from 50 feet to almost nothing. This calcareous deposit is 

 covered by sand to varying depths, and it stretches away from the Fish River valley 

 in which the railway runs towards the Kalahari. 



The calcareous rock is cut through by three rivers, roughly parallel with the Fish 

 River, namely the Auob, the Elephant and the Nossob rivers, and the river valleys 

 are marked by a series of low clifEs of the calcareous rock. The first discovery of 

 sodium nitrate was made at Witkranz in the Auob river valley lying roughly 50 miles 

 east and slightly north of Marienthal. Since then it has been found in the chfEs 

 for many miles along the Auob river and also in similar clifis along the Elephant and 

 Nossob rivers. The area thus covered is between 30,000 and 40,000 square miles. 



Upwards of five hundred specimens have been taken at wide intervals along all 

 three valleys, and practically aU contain sodium nitrate. The specimens are of two 

 kinds : (1) specimens of rock from the cHffs face — these are to some extent weathered ; 

 (2) specimens from the talus at the foot of the cliffs. 



These are obviously enriched secondary deposits. The first type contains sodium 

 nitrate in varying amounts from 1 to 23 per cent. The second type is much richer, 

 and specimens containing 90 per cent. NaNOj have been examined. Sodium chloride 

 is also present in considerable amount, but iodates appear to be absent. 



No investigation beyond this superficial examination of the clifE face and the 

 talus has yet been undertaken. The value of the deposits will depend on whether 

 (a) the calcareous rock as a whole contains nitrate, (6) the nitrate content increases 

 as one recedes from the cliff face. 



There is a good water supply available from artesian wells, which at present yield 

 10,000,000 gallons per day along the Auob river. 



Friday, July 26. 

 Joint Discussion with Section I (q.v.) on Vitamins. 



Prof. K. Freudenberg. — The Vegetable Tannins. 



The constitution of only two large groups, the gallotannins and the catecholtannins 

 has been completely determined by decomposition and synthesis. To the class of 



I 



