obtaini:d by the reaction of' Nitric Acid on Alcohol. 329 



importance may be inferred, viz. that in preparing the sji. 

 tsth. nitrici for medical uses, the distillation ought to be 

 stopped when oxalic acid appears in the retort, to avoid the 

 presence of aldehyd in the distilled fluid, and consequently 

 that the limitations with regard to the quantity of product 

 obtained, mentioned in the Pharmacopoeia, should be strictly 

 attended to, as the presence of so pungent and irritating a 

 fluid as aldehyd in the sp. seth. nit. of the shops, cannot but 

 interfere considerably with the cooling febrifuge uses of the 

 latter. I may remark, that as in the preparation of this aether 

 on the large scale it is of importance to the manufacturer to 

 obtain as large an amount of product as possible, we find, as 

 might be expected, traces of aldehyd in most commercial spe- 

 cimens of the ;tther, which indeed is indebted to it for that 

 pungent acrid flavour it so frequently possesses. If the di- 

 rections of the London Pharmacopoeia be observed, the pro- 

 duct is always free from aldehyd ; this I have verified in several 

 instances in nimierous specimens prepared in the pharmaceu- 

 tical laboratory of Guy's Hospital, as well as in that of mv 

 friend Mr. R. Phillips, of St. Thomas's Hospital. 



In conclusion, I may be permitted to submit the following 

 as the inferences deducible from the foregoing observations : 



1. That in the preparation of sp. aeth. nitrici, as long as 

 the latter with alcohol only distils over, no oxalic acid is 

 produced, an acid which appears to be identical with the 

 oxalhvdric only appearing in the retort. 



2. That on continuing the distillation beyond this point, 

 the free nitric acid in the retort reacts on the oxalhydric and 

 produces oxalic acid. 



.'3. That in the action of nitric acid on alcohol in the cold 

 as in Dr. Black's process for the formation of hyponitrous 

 aether, acetic acid is copiously produced, instead o\', or in ad- 

 dition to, oxalhydric acid. 



4. That aldehyd (as has been before shown by chemists) is 

 produced by the action of nitric acid on alcohol, but that it 

 is not formed in any quantity, or at least does not appear in 

 the distilled fluid, until the formation of hyponitrous aether 

 has nearly or altogether ceased. 



5. That the production of aldehyd and oxalic acid are 

 nearly simultaneous, and that both these appear to result 

 from secondary action of nitric acid upon products formed in 

 tiie early stages of the operation. 



G. Tliat the "crystals of Hierne" formed when distillation 

 is carried on until red fumes appear are oxalic acid, notwith- 

 standing their remarkable micaceous form ; and that the sub- 



