Mr Fenton, Soluble forms of metallic dihydroxy tartrates. 75 



the vessel may be inverted without loss ; in this behaviour 

 dihydroxytartaric acid resembles glyoxylic acid, the formula of 

 which is also generally represented as containing two hydroxyl 

 groups associated to the same carbon atom (compare Debus, loc. 

 cit. 1391). 



But if the dihydroxytartaric acid and calcium chloride are 

 both dissolved in anhydrous methyl or ethyl alcohol the solutions 

 remain perfectly clear on mixing and no separation occurs even 

 after standing for a day or two. A drop of water however will 

 immediately cause the formation of a gelatinous precipitate ; this 

 precipitate is mostly dissolved if more water is added but the 

 solution soon afterwards gelatinises. The action of small quantities 

 of water in bringing about the separation of the calcium salt is 

 so sensitive that it is quite easy by this reaction to detect the 

 presence of one or two per cent, of water in alcohol. ' Combined' 

 water, as in chloral hydrate or rrydrated calcium chloride, does not 

 produce a similar effect. 



