70 Oxalic Acid. — Diamonds. 



acid can act as a poison. The experiments, however, of Mr. 

 A. T. Thomson, " Medical Repository," remove all doubts on 

 this head. A solution of ten grains of oxalic acid thrown into 

 the stomach of a rabbit killed the animal in a few minutes ; a 

 drachm administered in like manner to a doy;, killed him in ten 

 minutes. The appearances on dissection were a pulpy state into 

 which the coats of the stomach were reduced. This state is in- 

 geniously conjectured by Mr. Hume to arise from a decompo- 

 sition of the phosphate of lime contained in the coats pf the 

 stomach. But however this may be, it appears undenial)le that 

 oxalic acid taken into the stomach acts as a virulent poison, 

 Mr. Royston has related a plain case : " A woman took about 

 four drachms of oxalic acid mistaking it for sulphate of magnesia. 

 Excessive tormina shortly ensued, and in forty minutes after 

 swallowing it she expired." A mixture of chalk and vvater, if 

 taken shortly after the oxalic acid, proves an antidote, !)V forming 

 an oxalate of lime in the stomach. The knowledge of this fact 

 is much more important than may be generally supposed, as 

 there is a number of persons in the habit of using a solution of 

 oxalic acid regularly, supposing or alleging it to be a cooling 

 beverage, an excellent remedy for the effects of wine or other 

 stimulants, and imagining that it improves their complexion, 

 and renders them proof against any contagion or infectious dis- 

 ease. Now that it is proved to be a potent poison, perhaps 

 they may discover that its greatest virtue is in tempting the han4 

 of death before nature designs it. 



Oxalic acid is very frequently sold in the shops for citric acid; 

 and as if to sanction this deception, it is vulgarly called the " salt 

 of lemons," altliough sorrel and sugar with nitrous acid are the 

 chief articles used in its formation. It crj'stallizes in slender 

 four-sided rhomboidal prisms, bevillod at each extremity; the 

 crystals are white, of an agreeable sour or tartish taste, and per- 

 manent in the air or slightly efflorescent. The crystals of citric 

 acid are not so white, of a sharp acid taste, almost caustic, and 

 permanent in the air, although inclining rather to deliquesce than 

 efflpresce. The crystals are rhomboidal prisms acuminated by 

 four planes, and much more sohible in water than those of oxalic 

 acid, boiling water dissolving double its weight of citric acid and 

 only its own weight oi' oxalic. / 



DXAMONDS. 



At the third annual course of lectures of the Birmingham 

 Philosophical Society which closed a short time since, a very 

 curious description and estimate of diamonds known to be in 

 existence, were given by Mr. Thonson. The number of known 

 diamonds of 36 carats and upwards, he stated to be no more 



than 



