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XXXV. Chemical Examination of the Tagua Nut or Vegetable Ivory. By 

 ARTHUR CONNELL, Esq., Professor of Chemistry in the University of St Andrews. 



(Read 15th January 1844.) 



THIS remarkable seed or nut is now well known in London, as a substance 

 extensively carved into a variety of ornaments, and capable of receiving as high a 

 polish as the finest ivory ; which it also greatly resembles in colour. I lately 

 obtained various specimens both of the nut in its natural state and of the fine 

 turnings produced in the process of working it, being desirous of submitting them 

 to a chemical examination. 



The nuts in my possession vary in size from a pigeon's to a hen's egg, and 

 have a somewhat angular shape. They are covered with a brown epidermis, and 

 have an outer shell & of an inch thick, and consisting of an outer white and an 

 inner brown layer. The inner mass of the nut is remarkably close grained and 

 homogeneous to the naked eye ; and when cut and polished exactly resembles 

 animal ivory. The hardness is considerable ; the white mass yielding with some 

 difficulty to a knife. Thin portions are translucent. The density of the white 

 mass is 1.376, at 53 F. 



Dr BALFOUR, Professor of Botany in the University of Glasgow, has been so 

 kind as to inform me, that this vegetable ivory " is the albumen (botanically 

 speaking), of a palm called Phytelephas macrocarpa, which is found on the banks 

 of the river Magdalena in the Republic of Columbia. The natives call it Tagua 

 or Cabeza de Negre (Negro's head)." 



Mr COOPER has described, in the Microscopic Journal,* the structure exhibit- 

 ed by a thin slice of this substance under the microscope. He found it to consist 

 of a homogeneous substance, without any appearance of cellular or other elemen- 

 tary structure, but traversed in one direction by parallel canals or tubes, some- 

 what irregular in their shape, and evidently filled with an oily fluid ; and he at- 

 tributes to the presence of these reservoirs of oil, joined to the compact texture of 

 the substance, the pure and lasting polish of which it is susceptible. 



I had made considerable progress in my chemical examination of this curious 

 substance, before I was aware that it had been submitted to analysis by my friend 



Vol. ii. P . 97. 



VOL. XV. PART IV. 7 G 



