Joseph Smith received revelation on tithing (D&C 119). (1)
-- 1838 July 8
John Taylor, John E. Page, Wilford Woodruff, and Willard Richards are called to the Quorum of the Twelve Apostles to fill vacancies caused by the excommunications of John F. Boynton, Luke S. Johnson, and Lyman Johnson, and William E. McLellin (see D&C 118). The twelve are also called to missionary work in England and were to leave on April 26, 1839. (2)
-- July 8, 1838
[Joseph Smith] Far West, Missouri. Joseph Smith received four revelations: Doctrine & Covenants 119 and 120 on tithing; Doctrine & Covenants 117 concerning the duties of William Marks, Newel K. Whitney, and Oliver Granger; and Doctrine & Covenants 118 on the will of the Lord concerning the Twelve Apostles. (3)
[Joseph Smith] Joseph receives a revelation concerning tithing and institutes it as a part of the Church. (4)
-- 1838 July 8
[Joseph Smith] Revelations on tithing and other subjects, Far West. (5)
-- July 8, 1838
[Revelations] . Doctrine and Covenants 117. Far West, Missouri.
N. K. Whitney and William Marks to Kirtland, sell property, pay debts. William is to preside over Far West. Newel's secret abominations, littleness of soul. Oliver Granger to be a merchant in Zion.
Scriptory Book heading, "Revelation Given to Wm. Marks, N. K. Whitney Oliver Granger & others. Given in Zion. July 8th 1838". (6)
[Revelations] . Doctrine and Covenants 119. Far West, Caldwell County, Missouri.
Tithing: All surplus to bishop, then 10% of annual interest.
Scriptory Book. (6)
[Revelations] Far West. Doctrine and Covenants Section 120. Time for a council of the First Presidency, bishop's council, high council. (6)
[Revelations] Far West, Missouri. Doctrine and Covenants 118. John Taylor, John E. Page, Wilford Woodruff, Willard Richards are called to fill vacancies in the Quorum of the Twelve. The Twelve are to leave Far West on April 26, 1839 to preach the gospel "over the great waters. ". (6)
[Revelations] Far West, Missouri. Revelation of July 8, 1838. Frederick G. Williams and William W. Phelps have lost their standing (priesthood and offices as counselor in the First Presidency and assistant president of the high council of Zion respectively). To be saved, they may be ordained Elders and serve missions abroad.
Also on this date, D&C 106, 117, 118, 120. These appear to be the last recorded revelations before Joseph and other leaders are taken prisoner and imprisoned in Liberty Jail.
Revelation Given July 8, 1838 in Far West, Mo. /.
Verily thus saith the Lord in Consequence of their transgressions their former Standing has been taken away from them,/.
and now. if they will be saved. let them be ordained as Elders in my Church to Preach my gospel, and travel abroad from land to land & from place to place to gather mine Elect unto me Saith the Lord. and let this be their labors from hence forth Amen/. (6)
-- 1838, July 8
[Wilford Woodruff] Called to the Quorum of the Twelve Apostles by a revelation to the Prophet Joseph Smith. (7)
-- about July 10, 1838
[Joseph Smith] Adam-ondi-Ahman, Missouri. Joseph Smith visited Adam-ondi-Ahman with the First Presidency, which consisted of Sidney Rigdon, his brother Hyrum Smith, and clerk, George W. Robinson. (3)
-- 14 July 1838
[Missouri War] Carroll citizens meet to oppose Mormon settlement at DeWitt. Meetings and threats against Mormons at DeWitt continue throughout the summer. (8)
1 - http://www.lds.net/forums/scripture-study-forum/12108-church-chronology-1800-2000-part-1-a.html#post214550
2 - http://en.wikipedia.org/wiki/19th_century_(Mormonism)
3 - BYU Studies Journal, volume 46, no. 4: A Chronology of the Life of Joseph Smith
4 - http://www.prophetjosephsmith.org/joseph_smith_timeline
5 - Joseph Smith Papers: Chronology for the Years 1832-1839
6 - http://saintswithouthalos.com/s/_dc.phtml
7 - Teachings of Presidents of the Church: Wilford Woodruff, The Church of Jesus Christ of Latter-day Saints, Salt Lake City, Utah
8 - Stephen C. LeSueur: The 1838 Mormon War in Missouri, Appendix: Chronology of Events in Missouri, 1838-1839