OLD RED SANDSTONE VOLCANIC ROCKS OF SHETLAND. 



387 



City Analyst's Laboratory, 

 138 Bath Street, Glasgow, 22nd June 1881. 



Analyses of eight Specimens of Shetland Igneous Rocks received from 

 J. Horne, on the 4th February 1881. 





1. 



2a, 

 2b, 2c. 



3a, 



3b, 3c. 



4. 



5. 



6. 



7. 



Grey Var. 



8. 



Pink Var. 





Porphyritc from 

 Roo 'ness Vop, 



contemporaneous 

 volcanic rock. 



Diabase between 

 Clonster and Aith 

 Voes, contemporan- 

 eous volcanic rock. 



■3 B 



11 



•gs"-g 



||| 



Granite from junc- 

 tion of Old Ked 

 Sa., Gruting Voe, 

 intrusive rock. 



3 g -3 



!* B 

 C 

 03 



0! O 

 OS'S? 



Cli a 



® e *o 



■a *j 



OS 5 



P..C 



a « 



Ch g 

 SB'S 



•— '-_ p 

 o oT '~ 





per cent. 



per cent. 



per cent. 



per cent. 



per cent. 



per cent. 



per cent. 



per cent. 



Silica, 



51-82 



48-36 



50-58 



71-66 



70-96 



6912 



73-70 



7232 



Alumina, .... 



14-14 



19-73 



15-51 



13-28 



1518 



14-55 



1334 



14-02 



Peroxide of iron, . 



5-50 



7-71 



5-74 



1-24 



1-69 



1-70 



1-06 



111 



Protoxide of iron, 



5-76 



4-68 



3-06 



•10 



absent 



•14 



•14 



•47 



Bisulphide of iron, 



absent 



absent 



•45 



absent 



absent 



absent 



absent 



absent 



Oxide of manganese, 



•25 



trace 



•29 



absent 



absent 



absent 



•10 



trace 



Lime, ..... 



6-10 



663 



9-52 



2-24 



1-52 



1-57 



233 



114 



Magnesia, .... 



1-76 



5-97 



8-90 



•64 



•70 



•52 



1-24 



•48 



Potash, .... 



7-81 



2-57 



•85 



4-84 



4-68 



10-17 



5-05 



7-44 



Soda, 



1-09 



3-47 



2-89 



537 



4-32 



1-27 



2-43 



2-53 



Phosphoric acid (Anhydride) 



•56 



•05 



13 



•18 



trace 



•05 



trace 



trace 



Sulphuric acid, „ 



•05 



absent 



•08 



absent 



•11 



•12 



•22 



absent 



Titanic acid, „ 



absent 



absent 



absent 



absent 



absent 



absent 



absent 



absent 



Carbonic acid, „ 



4-05 



•10 



1-28 



absent 



absent 



absent 



absent 



absent 



Water of combination, 



•91 



•53 



•51 



•30 



•66 



•67 



•27 



•40 



Moisture, .... 

 Specific Gravity, . 



•20 



•20 



•21 



•15 



•18 



•12 



12 



•09 



100- 



100- 



100- 



100- 



100- 



100- 



100- 



100- 



2-743 



2-788* 



2-911* 



2-609 



2-618 



2-540 



2-652 



2-621 



* Mean specific gravity of three pieces. 



Robert R. Tatlock. 



VOL. XXXII. PART II. 



3q 



