A second teenage boy has been arrested in connection with a spate of acid attacks which occurred in north and east London on 13 July.
The 15-year-old has been held on suspicion of grievous bodily harm and robbery following five similar attacks involving nitrous substances and a moped which occurred within a 90-minute timeframe.
Detectives previously arrested a 16-year-old boy for the same offences after he was identified near the scene by local authority CCTV operators. Both suspects are currently being held at a north London police station.
Chief Inspector Ben Clark, from Hackney Borough, said: "This is a fast moving investigation and we have made two arrests today. However, I would like to ask the public for their help.
"Each of these offences took place in busy locations and we know there may be witnesses who have not yet contacted us. If you saw something or managed to film or photograph anything that might help us please get in touch.
"These are hideous offences and must have been very frightening for all of the victims. I'm aware of rumours circulating that the victims were all food delivery riders set up in advance of the attacks. This is not the case. All victims were riding mopeds at the time of the attacks, but were from a variety of backgrounds.
"Of late we have seen more attacks using corrosive substances in London. I would urge businesses and parents to challenge those who they think may be trying to obtain or carry these substances as this could help prevent serious offences and life changing injuries being caused."
Police are continuing to appeal for information following the spate of attacks. The first one occurred at 10:25pm on 13 July on Hackney Road on the junction with Queensbridge Road in which 32-year-old male was attacked with a corrosive substance before having the moped he was riding stolen from him.
The second victim, a 44-year-old old man, had acid thrown in his face by two males also on a moped in St Paul's Road, N1 in Islington, near the border with Hackney, just before 10:50pm.
A 52-year-old man was also targeted on Shoreditch High Street just after 11pm. The victim was also riding a moped but the suspects again got away empty handed.
Around 15 minutes later, a 24-year-old male suffered life-changing injuries after acid was thrown in his face at Cazenove Road, N16 near junction with Upper Clapton Road.
The final attack occurred at 11:37, when a 33-year-old man had liquid sprayed on his face while he was riding his moped on Chatsworth Road.
Any witnesses, anyone with information or in possession of footage of these incidents should contact police via 101 or via Twitter @MetCC.
To give information anonymously call Crimestoppers on 0800 555 111 or visit crimestoppers-uk.org.