A 27-year-old male graduate student was injured with minor lacerations in a chemical explosion at the Chemistry Building at about 7:30 p.m. Friday, MSU police Lt. Kelly Beck said. The student was performing an experiment when there was a defect in the flask. There was no property damage and the victim refused transfer for further medical attention, Beck said.• A 19-year-old male nonstudent was assaulted while walking on the south side of Michigan Avenue near Harrison Avenue at about 2:40 a.m. Saturday, Beck said. The man was walking home from a house party when four men approached and asked the nonstudent's female friend for a cigarette. When she refused, the nonstudent intervened and was punched in the face. He received lacerations to the lip, tooth and elbows.• A 55-year-old female university employee reported a purse stolen from Morrill Hall, Beck said. The purse was left unattended and is valued at $55. Police have no suspects.• A 19-year-old female student reported a purse stolen from her West Holmes Hall room Friday between 9:30 and 10:30 p.m., Beck said. The total contents of the purse included a cell phone and wallet valued at $120. Police have no suspects.• A 19-year-old female student reported being bitten by a black, medium-sized dog while attending Party at the Aud on Saturday at the Auditorium, Beck said. The female student was bitten on the nose and was left with a small open wound. Beck said the woman chose not to seek charges against the dog's owners.• An 18-year-old male student reported being punched in the face between 2 and 4:30 a.m. at Emmons Hall, Beck said. The victim was transferred to Lansing's Sparrow Hospital with swelling and lacerations. Police have no suspects, Beck said.• Police were called to Akers Hall Friday at 11:45 a.m. to follow up on a complaint of possession of marijuana, Beck said. An 18-year-old male student was found with a small container suspected to contain marijuana by the residence hall staff. The container was turned over to the police, who are seeking a warrant from the prosecutors office, Beck said.