38 SOME NOTES ON ANCIENT MORTAES. 



combined influence of the adhesiveness of the mortar to the 

 stone, rendered more intimate by chemical combination, that 

 the full effects are obtained. 



The greater proportion of ancient mortars are firm and 

 durable, but this, however, is not the universal rule. An 

 instance of a mortar of inferior quality came under my 

 notice in 1888 when a mithrseum was discovered accidentally 

 at Ober-Florstadt. This was dug out at the desire of a 

 gentleman residing at Darmstadt, and it was found to be a 

 rectangle extending south to north. The interior space was 

 occupied by a depression approached by a descent of four 

 steps on the southern side. Several altars, figures, coins, 

 etc., were found and were removed to the museum at Darm- 

 stadt. Professor Adamy made carefnl examination of the 

 place, and came to the conclusion that the building was a 

 temple dedicated to Mithras, and was built about the mid- 

 dle of the third century. I analysed a small piece of the 

 mortar with the following result : — 



Per cent. 



Sand, insoluble in hydrochloric acid . . . 74-92 



Carbonate of lime 5'09 



Alumina and oxide of iron 8'61 



Carbonate of magnesia 1'02 



Sulphate of Hme 0*52 



Lime otherwise combined ..... 1'50 



Soluble silica 0-84 



Moisture and chemically combined water . . 7*20 



Chlorine trace 



Alkalies trace 



The carbonic acid present is not sufficient to completely 

 account for the lime and magnesia, so that a portion of these 

 must exist as hydrate, or more probably combined with 

 silica. There was 0*84 per cent, of soluble silica in this 



