30 years ago:

26 September 1988     President Reagan calls for a meeting of the Geneva Protocol states parties. Addressing the UN General Assembly, he says: "The use of chemical weapons in the Iran–Iraq war ... jeopardises the moral and legal strictures that have held these weapons in check since the First World War. Let this tragedy spark reaffirmation of the Geneva Protocol outlawing the use of chemical weapons. I call upon the signatories to that protocol, as well as other concerned states, to convene a conference to consider actions that we can take together to reverse the serious erosion of this treaty".[1] It is not immediately clear what sort of conference he has in mind,[2] although State Department officials had, some days earlier, told journalists that the United States had begun "sounding out other major nations about convening an international conference to roll back the growing use and threat of poison gas attacks".[3] Soviet Foreign Minister Shevardnadze tells the General Assembly that the Soviet Union "takes a positive view of the proposal"[4] and tells the media that it is "a very good idea".[5] The British Foreign Secretary, Geoffrey Howe, also expresses support.[6]
     President Mitterrand responds to the proposal by telling the General Assembly "my country, the depositary of the Geneva Protocol of 1925, naturally favours a meeting of the 110 signatories to that agreement. The purpose of such a meeting, in our view, would be to solemnly reaffirm the commitment not to use chemical weapons, to prevent their proliferation, to encourage new accessions to the Protocol, to improve investigative procedures — in short, to indicate a common desire for the success of the work currently being carried out at Geneva within the context of the Conference on Disarmament."[7]
     Neither Iran nor Iraq makes any reference to this proposal in their General Assembly plenary speeches.[8]
     Later in the day, President Mitterrand states that France is prepared to host the conference in Paris.[9] The initial suggestion in that it may be held in December,[10] but soon a decision is reached to convene it for 7–11 January.[11]
     [Note: President Mitterrand's speech also includes a statement that France "has no chemical weapons", seemingly the first such statement of this kind for this country.]
     [1] Ronald Reagan, President of the United States of America, speech to the 43rd session of the UN General Assembly, 26 September 1988, A/43/PV.4, p. 33. The text is also distributed as no 1109 in the State Department Current Policy series under the title "Prospects for a new era of world peace" with some minor variations, such as the use of the term "World War I" in place of "the First World War" in the above quote.
     [2] Lou Cannon (from UN New York), "Reagan urges halt to use of poison gas", Washington Post, 27 September 1988; John H Cushman, Jr (from Washington), "Chemical arms plan called a stopgap", New York Times, 28 September 1988, p A4.
     [3] Don Oberdorfer, "US tests waters for conference on poison gas", Washington Post, 21 September 1988, p 23.
     [4] Eduard Shevardnadze, USSR Foreign Minister, speech to the 43rd session of the UN General Assembly, 28 September 1988, A/43/PV.6, p. 73.
     [5] Julie Johnson (from UN New York), "US asks stiff ban on chemical arms", New York Times, 27 September 1988, pp A1 & A10.
     [6] Sir Geoffrey Howe, UK Foreign Secretary, speech to the 43rd UN General Assembly, 28 September 1988, A/43/PV.8, p. 62-3.
     [7] Francois Mitterrand, President of France, speech the 43rd session of the UN General Assembly, 30 September 1988, A/43/PV.10, p. 11-12.
     [8] Mr Ali Akbar Velayati, Foreign Minister of Iran, speech to the 43rd session of the UN General Assembly, 30 September 1988, A/43/PV.14, p. 59-82 and Tariq Aziz, Foreign Minister of Iraq, speech to the 43rd session of the UN General Assembly, 6 October 1988, A/43/PV.17, p. 144-60.
     [9] >Paul Lewis (from UN New York), "Mitterrand asks sanctions against users of poison gas", New York Times, 30 September 1988; Charles Lescaut and Claire Trean (from New York), "[Paris to host the conference on chemical disarmament]", Le Monde, 1 October 1988, pp 1 & 4.
     [10] [no author listed], "Paris to hold chemical war meeting", International Herald Tribune, 1-2 October 1988, p 2.
     [11] French speech to the First Committee, 20 October 1988.

35 years ago:

15 September 1983     A classified Special National Intelligence Assessment (SNIE) "Implications of Soviet Use of Chemical and Toxin Weapons for US Security Interests" is circulated within US government circles. The SNIE is prepared by the Central Intelligence Agency in collaboration with other US intelligence units.
     On Syria, the report states: "Syria, also a major recipient of Soviet CW assistance, has probably the most advanced chemical-warfare capability in the Arab world, with the possible exception of Egypt. Both Czechoslovakia and the Soviet Union provided the chemical agents, delivery systems, and training that flowed to Syria. As long as this support is forthcoming, there is no need for Syria to develop an indigenous capability to produce CW agents or materiel, and none has been identified."
     Some details appear to be first made public in August 1984,[2] with further details being published a year later.[3]
     [1] Central Intelligence Agency, "Implications of Soviet Use of Chemical and Toxin Weapons for US Security Interests", Special National Intelligence Assessment 11-17-83, 15 September 1983, (formerly marked "SECRET NOFORN/NOCONTRACT/ORCON"), approved for release in redacted form 28 February 1994, 20 + v pp.
     [2] Jack Anderson (with Dale Van Atta), "The Growing Chemical Club", Washington Post, 26 August 1984, pp C7.
     [3] Don Oberdorfer, "Chemical Arms Curbs Are Sought; Officials Alarmed By Increasing Use Of Banned Weapons", Washington Post, 9 September 1985, pp A1, 6 and 7.

70 years ago:

22 September 1948     The freighter Miervaldis is scuttled with a cargo that includes chemical munitions being disposed of by the United Kingdom [see 22 August]. The location is given as 47 23.00N, 09 24.00W at a depth of 4000 metres.[1]
     The cargo is described in media reports as the "last load of chemical warfare ammunition remaining in Britain" with the ship being the 17th used for the purpose, bringing the total sunk to "nearly 100,000 tons".[2]
     [1] UK Ministry of Defence, "British Isles Explosive Dumping Grounds", August 2005, available via http://www.mod.uk.
     [2] [no author listed], (from London), AAP, as in: "Ship to be scuttled with chemical arms", The Mercury (Hobart, Tasmania), 18 September 1948.