In a letter to Dr. Heddle, Capt. Marshall Hall writes—" On the next page I give you, in complement of my last letter, the analysis of a serpentine from the Saas Thal. For the specimen I am indebted to M. Henri de Saussure. It will be interesting to compare it on the spot, and study it in its relations to the accompanying rocks and minerals.

Whether the stone is fairly serpentine with so much iron is perhaps to be questioned ; I send the analysis as that of a "reputed " serpentine, and I send it to you as you have been doing serpentines, ... . as it is possible that additional data may be of use to you.