112 ' REPORTS ON THE STATE of science. 



decomposed by the acid, and it was found impossible to obtain C0ri j 

 cordant values, especially for the insoluble portion and for the magnesia. 

 It was therefore decided to try acetic acid instead, since this aci<jl dis- 

 solves calcium carbonate but does not readily attack silicates. This 

 method, as the following analyses indicate, was very successful, and is 

 evidently suitable for the analysis of metamorpbic limestones containing 

 silicates : — 



I. II. 



Residues insoluble in acetic acid .... 28-21 28-14 



Al. 2 3 +Fe. 2 3 0-08 0-17 



CaO 38-89 39-01 



MgO 0-53 0-46 



C0 2 31-08 31-12 



H 2 108 1-13 



99-87 100-03 



Percentage CaC0 3 69-44 C9-GG 



6. Red Limestone; Tyddyn Vu, Amlwch. 



I. II. 



Residues insoluble in HC1 14-97 15-13 



AljA+FejA 4-30 4-24 



CaO 27-51 27-60 



MgO 14-84 14-82 



C0 2 38-05 38-16 



99-67 99-95 



Percentage CaCO, 49-12 49-28 



MgC0 3 31-16 3112 



Several masses of peculiar limestone of this type occur in the schists 

 of the northern region. 



No. 550a. — Ironstone in Llandeilo shales, Llanbabo. Only the iron 

 has been estimated in this rock; the actual state of combination has not 

 been determined : — • 



I. II. 



Total Iron (calculated as Fe. 2 3 ) . . . .26-94 27-04 



This is an ironstone, sometimes very oolitic, which occurs in the 

 Nemagraptus gracilis shales, and may be of some importance. 



c. Massive Grey Limestone, in Old Red Series. 



I. II. 



Residues insoluble in HC1 9-11 9.04 



Al. 2 O s +Fe< 2 3 0-88 0-97 



CaO 50'15 50-22 



MgO — — 



C0 2 39-59 39-65 



99-73 99-88 



Percentage CaC0 3 89-55 89-68 



