972 



origin i. e. a product of a morphological change of the above grains. 

 Also from this fact it 'appears that the segregations sometimes, so 

 to speak, erode the grains. It is also remarkable that those prisms 

 and neeilles extinguish "einheitlich", but present aggregate polarisation, 

 from which we conclude that I hey have undergone a molecular 

 conversion and belong to a compound of only little stabilitj-. 



A mechanical separation of the two substances was impracticable 

 in consequence of their softness. While being rubbed in the mortar 

 they were completely mixed up. 



The number of analyses of concretions is not lai-ge. They have 

 been tabulated on the next page. N". I is made by D. Pi,es^), nVII 

 by Prof. Abki,'), n". Ill and IV by G. Thoms'), while n'. V of the 

 substance described above was carried out in the Heidelberg Chemical 

 Laboratory of Prof. M. Dittrich. 



The analyses carried out by Plks, Abkl aiul Thoms revealed that 

 the concretions from teakwood consist of an aqueous calcium, 

 pliospliate, of a composition about similar to that of 7iri<.vA/^« *), which 

 theoretically is composed as follows: 



* P'-O' ....... 41.28 



CaO 32.55 



H'O 26.17 



10ÜX>Ö, 

 which corresponds to the formula HCaPO^ -\- 2H'0. 



The di (Terences in tlie various results of the analyses may be 

 accounted for by the fact that some admixtures were overlooked 

 and also that the methods of estimating the constituents, which were 

 then in use, involved errors that could not be avoided. 



Thus far experience had taught that the composition of the secretions 

 in plants is very constant. We need only remember \\\e. mestika aioi 

 (tabaschir), the mesticd kalapd, the secretions from calciumcarbonate 

 known by the name of cystoliles, and lastly the crystallizations of 

 calcium oxalate. 



^) Onderzoek naar de samenstelling eener witte stof, welke zich in het hart, 

 alsmede in de scheuren van sommige djaliboomen afzet. (Naluurk. Tijdschr. 

 Ned.-Indië 15, Batavia 1858. p. 845 — 348). The recalculation is mine. 



') .1. S. Gamble. A Manual of Indian Timbers, New Ed. London 1902, p. 583. 



') G. Thoms, Beilrag zur Kenntniss des Teakholzes (Tectonia grandis), Die 

 Landwirthschaftl. Versuchsstationen 23, BerHn 1879. p. 416 — 417. 



*) G. E. Moore. On Brushite, a new mineral occurring in Phosphatic Guano, 

 Proceed. California Acad, of Nat. Science 3, 1867. San Francisco 1868. biz. 167 — 168; 

 Amer. Journ. of Sc. (2) 39, New Haven 1865, p. 4:i — 44. — A de Schulten, 

 Becherches sur le phosphate dicalcique. Reproduction aitificielle de la brushite. 

 Bull. Soc. fran^. de Mineralogie 26, Paris 1903, p. 12. 



