A second teenager has been arrested over an acid attack that left a delivery driver critically injured.
The 32-year-old could lose his sight following the assault in Walthamstow, east London, on Thursday evening.
A 16-year-old was arrested on Saturday night on suspicion of grievous bodily harm. A 14-year-old held on Friday has been released under investigation.
In another attack in Tottenham on Thursday, a second delivery driver had a corrosive substance thrown at him.
Police "strongly suspect" the attacks are linked, the BBC's home affairs correspondent Danny Shaw said.
He added that the victim in the first attack - who was injured as two males tried to steal his moped - had injuries to his throat, face, oesophagus and eyes and had been in an induced coma.
Police said the suspects demanded he hand over his keys, and when he refused a struggle followed.
"This attack has left a man fighting for his life and with terrible eye injuries," Det Ch Insp Gordon Henderson said.
"This was an innocent man going about his work as a delivery driver, who may never see again."
In the second attack, two males approached a delivery driver on Yarmouth Crescent in Tottenham, north London, in a bid to steal his moped.
He was taken to hospital but his injuries are not thought to be life-threatening.