?!• I0» Mortars, Water lime, Cenunii, fjf(. 



• Mortar of Lafqye. 



* 



In 1777, tafaye publiflied his enquiries into the preparation which the Romans gave to 

 their lime, and the compofition of their mortars. The praftical part is extrafted, with 

 much detail, in the Journal de Phyfique, IX. Part I. p. 437. 



The eflential article is the method of flaking the lime without liquefying it, in order to 

 hare a powder, and ftill fufficiently cauftic to afford a very ftrong lime, which (hall grow 

 hard with age. 



For this purpofe good freCh lime, made from hard ftone, is taken and hroken into pieces 

 about the fize of an egg } thefe are thrown into an open builc r, which is plunged into 

 water, and kept there till the furface begins to boil ; at which period it is taken out, and 

 fuffered to drain, when the lime is thrown into caOcs, where it heats, and falls into 

 powder. 



This lime, fo prepared, is taken as an ingredient in various kinds of mortar, according 

 to the objeft. It keeps very well when the calks are covered with ftraw. 



I have ufed this lime in tlie conftruClion of a fmall aquedu£t of more than fifty metres 

 in length, intended to convey water to an artificial nitre bed near Dijon, about e'ghtcen 

 years ago. The mortar made of three parts of fand, and three of cuttings of hard lime 

 ilone, became very firm and folid in a (hort time, though it was under ground. 



•Concerning Poor Lime, or PFater Lime [Chaux Maigre), 



In fome countries they have a kind of Jime called poor lime, becaufe in equal quantities 

 It does not give a mortar as fat as the others ; but this lime has a property which renders 

 it very valuable, namely, that of becoming folid and hard under water. 



The caufe of this property was unknown till Bergman obferved that it is owing to a 

 oxide of manganefe, which the lime ftone of Lena contains in the proportion 0.02, as do 

 likewife other ftones that form a mortar capable of hardening under w^tcr. Opufc. II. 

 Eflay XIX. §. 10. 



In 1783, I publifhed, in the fecond feir.eftre of the new memoirs of the academy of 

 Dijon, page 90, experiments on fix fpecies of this kind of lime ftone, among which was 

 the lime ftone of Lena, which had been fent me by Bergman. Two among them only 

 affumed by calcination the brown colour which charadlerifes manganefe, and underwent ^ 

 comparative effays with the lime ftone of Lena. 



Independant of the poor lime ftone indicated in that memoir, namely, thofe of Lena, 

 Brion, in the department of Saone et Loire, at the diftance of five kilometres from Autun, 

 and of Morex, near Geneva, I am at prefent acquainted with two others, viz. i. that 

 employed at Metz, in the works under water, of which the analyfis was made in the 



courfc 



