On MoriArSy Wattr Lime, CemetiU, {jfcr Itz 



courfe of the polytechnic fchool in the year 6 ;* and, 2. that which Smcaton, con- 

 ftruftor of Eddyftone light-houfe, has defcribed in his account, which was obtained 

 from Aberfliaw, in the county of Glamorgan^ Bibl. Britanique, September, 1796, 

 page 102. 



I have no doubt but that (tones of the fame quality may be found in many other placfes, 

 and in the territory of the French republic f, that is to fay, containing manganefe, and 

 naturally mixed with a quantity rather confiderable of filex and alumine 5 for it is evident 

 that this laft condition contributes to afford a poor lime (lone, or mortar, nearly prepared' 

 by nature, and unfit to be mixed with any confiderable quantity of fand, or cement, or 

 - other dry matter. 



.Artificial Water Lime {Chaux Afaigre). 



I have long ago propofed to ufe, in cafes when the natural lime ftone is not to be had, a 

 mixture of four parts of grey clay^ and fix of the black oxide of manganefe, with ninety 

 parts of good lime ftone reduced to a powder. 



This mixture,, after having been well calcined and cooled, is worked to the confiflence 

 of foft pafte, with fixty parts of filex. 



In the laboratory of the polytechnic fchool is preferved a ball of this mortar thus pre^^^ 

 pared, according to the above proportions, at the fitting of the 29 Pluviofc, in the year 5, 

 which was immediately thrown into water, where it hardened, and acquired the fpecific 

 gravity of 2.231. 



A very good water lime may be procured flill more cheaply by mixing, with common 

 quick lime, a certain quantity of the white iron ore, which is found plentifully, and is in' 

 great part compofed of carbonate of lime with manganefe, more efpecially thofe whichs 

 are poor in iron. 



It is pofFible, as De SaufTure obferves in his travels in the Alps, that there may be flones,. 

 which though they contain no manganefe, may from fome other particulars of their com- 

 pofition, neverthelefs afford lime capable of hardening under water, fuch as the afhes Cen- 

 dree of Tournay, mortar made with the trafs of the Hollanders, &c. But this in no re- - 

 i^e£t weakens the refults of obfervations and experiments on the efficacy of the oxide of 

 manganefe; as for inflance that of common mortar, which without this addition wo uldT 

 immediately become diffufed in water, but hardens very fpeedily when a certain dofe of 

 that oxide enters into its compoCtion. Mr. Smeaton here affords us an important remark, 

 namely, that balls made of lime and fand well worked together, and then put into waterj, 

 were deftroyed, whatever were their proportions (Loco cit.) 



* In this analyfis it was found to contain in the hundred carbonic acid 39.0 ; lime 44.5. j. filex .5.25 j- 

 alumine 1.25 ; manganefe 3.5 j oxide iron 3.2 j water 2.25 ; lofs 1,05. 



f Citizen Lomet found a quarry at Saintr^s, in the department of Lot-et-garon, which has bfeen fuc-. 

 cefsfully employed in building under water. 



Concerning 



