On the 10th of September Mr. Gorsuch, a citizen of Maryland, accompanied by several officers and other persons, proceeded from Philadelphia to Christiana, near Lancaster, for the purpose of arresting two negroes claimed under a law of the United States as fugitive slaves. In order to resist the execution of the law the negroes of the vicinity rallied to the number of seventy or eighty, armed themselves with guns, and fired on the party of whites, killing Mr. Gorsuch, and mortally wounding his son. The negroes were also considerably injured by a discharge from revolvers by the party with the officers. It appears from a statement published by the Rev. Mr. Gorsuch, a son of the claimant of the negroes, that a conspiracy was planned beforehand, to resist the officers of the law in the execution of their duty; and that it was not confined to the negroes, but was apparently under the guidance and control of whites. Mr. Gorsuch says that while the officers were awaiting the decision of the blacks, a white man rode up; that his presence seemed to inspire the negroes with renewed hostility; that he refused, when summoned, to aid the officers, and threatened them with bloodshed if they persisted in executing the law. It is further alleged that it was after receiving some communication from this person that the negroes rushed on the officers and killed Mr. Gorsuch. Since then a correspondence on the subject has been held between the national executive and the executives of the states of Maryland and Pennsylvania. The slaves have not been recovered, but many arrests have been made of persons charged with conspiracy to prevent the execution of the laws, and with treason. The Free Soil party of Massachusetts, at a State Convention, held Sept. 16, nominated for Governor, John G. Palfrey, and for Lieutenant-Governor, Amasa Walker. The nomination for Governor was first tendered to Stephen C. Phillips, of Salem, who declined. The democrats held their State Convention on the 26th of August. They passed resolutions decidedly in favor of the Union, and against all anti-national and anti-sectional agitation. George S. Boutwell was nominated for Governor, and Henry W. Cushman for Lieutenant-Governor, and Charles G. Greene, Henry H. Childs, and Isaac Davis, were appointed delegates to the National Democratic Convention, which was recommended to be holden at Baltimore in May, 1852. The Whig State Convention was held at Springfield on the 10th of September and, on the first ballot, Robert C. Winthrop was nominated as their candidate for Governor, and George Grinnell as their candidate for Lieutenant-Governor. The proceedings were very harmonious, and the address of the chairman, and the resolutions passed by the convention, were of a strong national and Union character. Edward Everett, George Ashmun, and Seth Sprague, were chosen delegates from the State at large to the National Whig Convention.