114 FARxM BUILDINGS. 6. 



ii'^d) from common fand. I was at a lofs to 

 jtfcertdin their nature, until pounding feme 

 freeftonc, and vvailiing it in the m.anner I had 

 done the rciiduum, 1 found it to refemble ex- 

 adtiv the forty-two grains of wafhed grit of 

 the experiment. It appears to have been 

 pounded or ground very fmall, and to have 

 been put through a fine fieve •, the whole 

 being in a l\atc oi grit ; no fragn-^ent fo large 

 as 2 pin's head. 



It is obfei vablc, that the cement of this 

 experiment is weaker than that of the laft : 

 but whether from the nature of the hafe^ or 

 fjom the froportion of lime being lefs, or 

 from the two united, is not evident. 



Ii is alio cbfervable, that in the decompo- 

 fuion of this fpccimen a urinous fmell rofe 

 during the folution ; and that the edges of 

 the full filter attrad moillure from the air. 

 It is at prcfent a prailice among fome plaf- 

 lerei 5 to make ufe of urine in the prepara- 

 tion of plaftcr. 



Exi*. 3. Cement OF Pickering Castle : 

 taken from the ruins of the old cuter iva'tl 

 tricing the northweft. Colleded in three or 

 four different places •, a few feet above the 



foundation ; 



