60 



strata, that possibly the animal matter of the animals originally in- 

 cluded in the rock might have played some part in its consolidation, 

 and thus, after their destruction as living animals, they might have 

 continued to serve a useful purpose. 



After many unsuccessful experiments, made with common lime, 

 and raw animal or vegetable matter, she had recourse to sulphate of 

 lime, and found that plaster of Paris, when mixed with water, and 

 with not more than xAgth part of the weight of the whole mass of 

 mixed animal and vegetable matter, it did not set instantly, but con- 

 tinued for some hours quite plastic, developed, in setting, more heat 

 than usual, and finally acquired a remarkable degree of hardness, 

 and the power of resisting both water and fire to a very great degree. 

 A specimen, was exhibited, made in this way. 



In other specimens, three parts of sand had been mixed with one 

 of gypsum, and g'^jth of the whole of iron had been added, with the 

 same amount as before of oi'ganic matter. One specimen had been 

 exposed for two years to running water, and was but little affected. 



Time and exposui-e have a most remarkable effect in increasing 

 the hardness and compactness of these mixtures. 



Specimens were shewn of Arran granite, broken down and re- 

 consolidated by means of i^th of gypsum, and the usual propor- 

 tion of organic matter. One of these has even taken a certain 

 amount of polish. The author suggests, that possibly granite may, 

 in some cases, have been brought into its present state, not by 

 fusion, but by the combined agency of fire and water. She expects 

 a favourable result from an attempt to consolidate gi'anite without 

 gypsum, which is now in progress. 



Marine sands may be consolidated by the same means as those 

 above employed, but more slowly. Several specimens were ex- 

 hibited, one with an alga imbedded and well preserved. Liquor of 

 mussels and sea- weeds were found to yield sufficient animal and ve- 

 getable matter to effect consolidation. 



In several specimens, star fish and other moUusca were imbedded, 

 and generally continued distinctly visible. They also discharged 

 the colour of iron from the parts surrounding them. 



The animal and vegetable matter used by the author was glue 

 and starch, in her first experiments with gypsum ; but in those 

 made with marine sands, and those in which remains were imbedded, 

 she employed the animal matter contained in the liquor of mussels. 



