VOL. VI.] PHILOSOPHICAL TRANSACTIONS. 5S5 



Stance whereof we may observe in the seed husks of glastum, and the use dyers 

 make of the leaves after due preparation. 3. It is probable from the same in- 

 stance, that we may learn from the colour of some part of the fruit or seed, 

 what colour the leaves of any vegetable and tlie whole plant might be made to 

 yield for our use. 4. That the latent colours of vegetables are pre-existent, 

 and not produced ; from the same instance ofwoad, and likewise from this, 

 that the milky juice of lactuca sylvestris affords itself a red serum. 5. That 

 the change of colours in flowers is gradual and constant. 6. That the colours 

 of flowers, which will not stand with lye, seem to be wholly destroyed by it, 

 and irrecoverable : Thus it happens, in the experiment, that one part of a 

 violet leaf, upon the afl^usion of lye, is changed very soon into yellow, and 

 will never be revived into a red by an acid salt ; but if another part of the same 

 leaf be still green, it will be revived. 7. That the dryness seems to be a means, 

 if not of fixing, yet bringing the vegetable colour into a condition of not wholly 

 and suddenly perishing by the otherwise destroying alkali. 8. That those 

 plants or animals that will strike difl^erent and yet vivid colours upon the affu- 

 sion of different salts, and stand, as the cochineal and glastum, are probably 

 of all others to be reckoned as the best materials. 



In the concluding part of this communication, the author observes that he 

 has found out a colour most exquisitely black, and comparable to the best ink, 

 even for the pen, and which will not change by fire or salt. 



An Account of some Books. N° 70, p.2lS6. 



I. Theodori Kerkringii, M. D. Anthropogeniae Ichnographia, sive Confor- 

 matio Foetus ab ovo usque ad Ossificationis principia, in supplementum Osteo- 

 geniae Foetuum. Amstelodami, 1671, 4to. 



After that this author had the last year published, together with a spicile- 

 gium anatomicum, his osteogenia foetuum (of both which an account was 

 given No. 54, p. 413 of this volume;) in the latter of which he described the 

 formation of the bones of the human body, from the second month after con- 

 ception to the very time of the infant's birth ; he considered, that there were 

 two things yet left behind, necessary to the perfect knowledge of ossification ; 

 viz. 1st. What might be the rudiments and form of a human body, before it 

 came to have any firmness of bones. 2dly. How after an infant's being born, 

 the soft bones acquire by little and little both their hardness and magnitude. 

 Waving for the present the latter of these two, he undertakes in these sheets 

 to deliver the first elements, as it were of our body, from and even before the 

 time of conception ; affirming, 



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