T. 11. Chatard—Urao. 61 



but that on the contrary, the salts were uraos with a widely 

 varying excess of one or the other of the two carbonates. A 

 repetition of Winkler's* method for the artificial production of 

 sodium sesquicarbonate gave additional proof, for the salt ob- 

 tained was physically and chemically a urao having an excess 

 of NaHC0 3 as would be expected from the conditions of this 

 formation. Hence the conclusion that there is no such salt, 

 either natural or artificial, as sodium sesquicarbonate, but 

 that the true salt is a union of one molecule of Na 2 CO s with 

 one of NaHC0 3 , although the presence of an excess of ]STaHC0 3 

 may occasionally give results approaching the composition of a 

 sesquicarbonate. Many analyses, notably those of Wallace,! 

 who suspected the non-existence of sesquicarbonate, show uraos 

 containing an excess of Na 2 C0 3 while de Mondesir^: was the 

 first to publish a method for the artificial production of the pure 

 salt to which, on account of the relation of 3N0 2 to 4C0 2 , he 

 gives the name " carbonate quatre-tiers " or " four thirds car- 

 bonate." It might be called the " tetra-trita " or " tetrita- 

 carbonate." 



The five salts now to be described, were obtained by spon- 

 taneous solar evaporation of natural water and hence are " min- 

 erals." Nos. 1 and 2 are from the same specimen and were 

 formed in an artificial ground vat. When the water of Owens 

 Lake is allowed to evaporate, the first crop obtained is granular 

 crystalline and retains much mother liquor. The mother liquor 

 is therefore drawn off and this first crop, as far as practicable, 

 redissolved in lake water, thus forming a new solution which de- 

 posits a sheet of crystals much larger and purer than the first 

 product. The specimen of this sheet taken for analysis was 

 about two inches thick ; the upper portion was well crystallized 

 and translucent (No. 1 ) ; the intermediate part showed an inter- 

 lamination of thin, translucent, crystallized sheets and of fine- 

 grained crystalline, white material (No. 2), the undissolved por- 

 tion of the first product ; the bottom part of the specimen was 

 a layer similar to the upper portion but thinner, the crystals 

 being much smaller. No. 1 presented a radiated columnar 

 structure, the crystals being so grown together that the termina- 

 tions alone were visible and these so combined that each com- 

 bination had a curved ridge-like termination or cock's-comb 

 form. The specific gravity of this material was 2-1473 taken 

 in benzol at 21-7° C. 



No. 3 or "Twig" was formed on a branching grass-root which 

 chanced to be suspended in the water of a small lagune on the 

 east side of the lake. It has the form of a stout twig or of a 



* Winkler, Buchner's Repert. f. Pharm., xlviii, p. 215. 



f Wallace, Chem. News, xxvii, p. 203. 



\ De Mondesir, Comptes Rendus, civ, p. 1505, May 31, 1887. 



