=The New York Botanical Garden’s Museum.=--The museum building of the New York Botanical Garden is substantially completed, and most of the works are in an advanced state of forwardness. The museum cases (for public inspection) and the herbarium cases (for students) are in position, and the herbarium cases are filled. Among the recent gifts of value to the institution are the miscellaneous collection of John J. Crooke, made about thirty years ago and containing about twenty thousand specimens, among which are a set of the plants obtained by the United States Pacific Exploring Expedition of about 1850; the collection of between twenty and thirty thousand specimens made by Dr. F. M. Hexamer in Switzerland and the United States; a collection of seven or eight thousand numbers, made by Mr. and Mrs. A. A. Heller, representing between twelve and thirteen hundred species, some of which are new to science; and specimens of crude drugs, for the Economic Museum, presented by Parke, Davis & Co. A permanent microscopic exhibition is to be established by Mr. William E. Dodge, at his own expense. It will be furnished with at least twenty-five microscopes, and with specimens carefully prepared and inclosed, to secure them from injury. A set of more than two hundred volumes on botany and horticulture, which formed a part of the library of Dr. David Hosack, founder of the first botanical garden in New York, has been presented by the New York Academy of Medicine, which received it from the New York Hospital. * * * * * =Action of Sea Water on Cements.=--As the result of examinations of many masonry structures immersed in sea water, Dr. Wilhelm Michaelis has found that Portland cement does not resist the chemical action of such water so well as do Roman cement and the hydraulic cements. The soluble sulphates in the sea water appear to enter into a substitution combination with the lime which exists in the cement in a free state or is liberated in the hardening, and it is converted into a sulphate, while disintegration ensues. In Roman cement the lime exists in combination, and there is no inclination toward the formation of a sulphate, and hydraulic limes resemble Roman cement in physical qualities. Dr. Michaelis suggests that hydraulic cementing materials containing more lime than is required for the formation of stable hydro-silicate and aluminate may be made suitable for submarine work by an admixture of trass or puzzolana, whereby the cementing strength of the mass will be greatly increased, and it will be enabled to withstand the disintegrating action of the sea water. * * * * *