18 PEEMO-CAEBONIFEEOUS FOSSIL CLIFFS. 



Appendix A. 



Government Laboratories^ 



JHohart^ ith September, 1900. 

 Dear Sir, 



The samples of cement received from you on the 14th ult., and 

 stated to be from Maria Island, have been examined, with results 

 following : — 



12 3 



No. 1, cement; No. 2, blue lias clinker; No. 3, crumbling cement 

 brick, 10 years old. No appreciable amount of phosphoric acid 

 was found in -any sample ; a sni-all quantity only of sulphate of lime 

 is included in tlie lime. 



To render the results more strictly comparable, they have been 

 calculated, excluding the carbonic acid and water lost on ignition in 

 each case, as follow : — 



12 3 



Silica, soluble 27 



Silica, &c., insoluble 



Oxide of iron 



Alumina 



Magnesia 



Lime, &c 



100-00 100-00 100-00 



Variations in compositions of cements from several different 

 countries are added for comparison : — 



Per cent. 



Silica 19-9 to 26-1 



Alumina 5-2 „ 10-6 



Oxideofiron 2-1 ,. 5-0 



Lime 59-1 ,', 67-3 



Magnesia 0-3 „ 3-5 



Sulphuric acid 0-3 „ 4*2 



It will be seen that in the Maria Island material the silica is rather 

 above the maximum, and the alumina rather below the minimum 

 given above. Alteration in these respects would probably mean 

 improvement, but I am inclined to attribute the crumbling of 

 sample No. 3 to mode of preparation of the cement, as there are 

 some limestones which will yield cement or lime according to the 



