_Fifty-fifth_, to Francis C. Hayward and J. C. Bickford, of Colchester, Conn., March 19, 1850. For process of rolling India-rubber cloth. The “claim” is a new or improved process of applying rubber to cloth, by means of rollers; the process being a combination of the method of spreading rubber by the pressure of rollers, and the method of grinding and spreading, at one and the same time, against and into the substance of the cloth. _Fifty-sixth_, to John Pridham, Assignor to Horace H. Day, New York, March 19, 1850, for use of oxide of tin, in the manufacture of India-rubber. He does not claim the combining of ochre or pipe clay with India-rubber, or submitting rubber to high heat, or mixing sulphur with rubber. The specific claim is, the combining rubber with tin, as set forth, and the combination of these with sulphur and heat, whereby is produced a fabric having a black surface, which is capable of withstanding all the elements which distinguish vulcanized from other preparations of rubber. _Fifty-seventh_, to Fowler M. Ray, New York, April 2, 1850. For springs for cars, &c., of India-rubber. A method of making cylinder or rolls of prepared India-rubber, by rolling up a thin sheet of India-rubber, on a mandrel, while the sheet is in a green state, and as it comes from the heated calendering cylinders, substantially as described. He also claims a mandrel or cylindrical rod pressed against the periphery, or a cylinder or roller, so that the thin sheet of prepared rubber in the green state, and taken as it comes from the calendering cylinder, may be wound upon the mandrel, and the several windings made to adhere, by pressure, substantially as described. _Fifty-eighth_, to S. T. Armstrong & C. J. Gilbert, of New York, N. Y., for improvement in the process of working gutta-percha. Sept. 17, 1850. What we claim under the first part of our invention, consists in the use of lime or other alkaline substance, with heat, in the manner substantially as herein described, in the cleaning of gutta-percha, to neutralize the acid or acids contained in that substance in its crude or native state, and thus preserve and render more permanent its useful properties, as specified. And in the second part of our invention, we claim compounding lime with gutta-percha, substantially as herein described, for the purpose of improving its qualities, preserving it wholly or partly from deterioration, and protecting it against the injurious effects of the atmosphere and heat, substantially as described.