certain Tartrate Solutions. 275 



Accepting the hypothesis just brought forward the be- 

 havior of the tartrates of the alkalies and of antimony and 

 thallium with inactive salts can readily be explained as cases 

 of substitution. The phenomena of substitution are so charac- 

 teristic in many instances that in my last paper I was led to 

 suggest an application of these principles as offering a means 

 of analyzing certain salt mixtures, and before the matter ap- 

 peared in print the able article of Schtitt (Berichte, 1888, 

 p. 2586) came to hand, in which the quantitative analysis of 

 mixtures of potassium and sodium chlorides by means of their 

 action on neutral potassium tartrate was worked out. The 

 principle can undoubtedly be extended to the analysis of many 

 other substances. 



All these cases, however, appear simple when compared with 

 that of the potassium boro-tartrate. Here we have a compound 

 with large specific rotation which increases rapidly with the 

 concentration and also on addition of inactive substances. Any 

 substitution for the boron radical which we can imagine would 

 leave a molecule with decreased rotation, but it is possible that 

 there may be both addition and substitution and in a manner 

 which may account for the observed increase. A solution of 

 neutral potassium tartrate containing 10 gm. in 100 cc. gives 

 the rotation in the 400 mm. tube 



a=10°'788, £=22°-4 



A solution of 10 gm. of the same tartrate plus 10 gm. of KC1 

 gives under the same conditions 



a=ll°-238 



It is possible that the two substances have united in some way 

 here to form a complex group with increased rotation, and it 

 may be that with the boro-tartrate a similar group is formed. 



The other supposition possible is that the boro-tartrate is 

 wholly or in part decomposed, and if so it must be according 

 to this reaction, or a similar one, 



KBOC 4 H 4 6 + NaCl + 2H 2 0=KN aC 4 H 4 6 + H 3 B0 3 + HC1. 



One of the experiments given above shows that free boric 

 acid greatly increases the rotation of the boro-tartrate, and in 

 view of this I thought it well to test the probability of the 

 above equation. If a decomposition takes place in this man- 

 ner the same rotation should be found by using the equivalent 

 amount of Rochelle salt, boric acid and hydrochloric acid as 

 indicated. 1 dissolved in 100 cc. 



14-1 gm. KNaC 4 H 4 6 .4H„0 

 31 gm. H 3 B0 3 

 1-82 gm. HCI, 



